JPH03225253A - Micro-indentation type method and device for testing physical property of material - Google Patents

Abstract

PURPOSE:To accurately and easily measure the physical property of an extremely shallow part in the vicinity of the surface of a material by measuring relation between the load of indentation and drawing processes and indentation depth. CONSTITUTION:A measuring/control circuit 90 controls a load current supplying device 43 in accordance with a previously set pattern to increase a load current (i) to be supplied to a solenoid 42 and indentation load to be applied to an indenter 36. The indenter 36 is successively indented to the surface of a material to be tested, and when the indenter 36 is indented up to the prescribed indentation depth, the current (i) is reduced to reduce the indentation load. Thereby, the indenter 36 is successively drawn out. In the indentation and drawing processes, the indentation load F of the indenter 36 is measured based upon the current (i), the indentation depth (d) is measured based upon a signal outputted from an indentation depth detector 50 and the relation between the load F and the depth (d) is measured continuously or in stages and stored in the circuit 90. Thus, physical properties such as tensile strength and Young's modulus in the vicinity of the surface of the material to be tested are calculated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method and apparatus for measuring physical properties such as mechanical properties near the surface of various solid materials.

More specifically, the present invention injects an indenter into the surface of a test material to a very shallow depth with a small load, changes the load when pushing and pulling out the indenter, and adjusts each load and indentation depth by δ or 1. Or, while changing the indentation depth of the indenter, the indentation load required for this indentation is determined as 4PJ, and from this 4-1 relationship between the determined indentation load and indentation depth, the physical properties near the surface of this test material are determined. It is used to measure.

[Prior art] In various industrial fields, a few micrometers near the surface of solid materials are used.
There is a need to measure physical properties such as mechanical properties of the parts. For example, in the field of the nuclear power industry, in order to understand the deterioration of the surface of materials due to radiation, changes in characteristics, etc.
It is necessary to determine 4-1 the physical properties near the surface of this material. In addition, such measurements are also necessary when measuring the physical properties of thin synthetic resin films or when determining the physical properties of coatings, paints, etc. Furthermore, in the field of semiconductor industry, it is necessary to measure the physical properties of thin films of circuit patterns deposited on the surface of chips.

Conventionally, the physical properties near the surface of such test materials were determined by 71-1.
A microhardness tester is used to determine the hardness. This micro-hardness tester is basically the same as the conventional hardness tester, but the load applied to the indenter is several tens of mg, the indentation depth of this indenter is extremely shallow, and only the physical properties near the surface of the test material are measured. 1l
llJ can be determined.

However, when the indentation depth of the indenter becomes extremely shallow in this way, the accuracy of the hardness determined by 4Pj is greatly reduced. In other words, at the very early stage when this indenter starts contacting the surface of the test material, the deformation of this surface depends on the shape of the indenter and is mainly composed of elastic deformation, and the indentation corresponding to this indenter becomes smaller. , an error occurs in that the apparent upper hardness becomes extremely high. Furthermore, surface roughness also causes such measurement errors. If the indentation depth of the indenter is extremely shallow as described above, it is not possible to separate and estimate the plastic deformation using conventional methods, and therefore it is not possible to accurately evaluate hardness or tensile strength. could not.

As an improvement on the conventional method, [JP-A-62-
There are microhardness meters as disclosed in ``No. 69141'' and ``Japanese Unexamined Patent Publication No. 62231136.'' These devices push the indenter while changing the indenter's indentation load.
The purpose of this method is to measure the relationship between each load and the indentation depth continuously or stepwise to reduce errors.

However, these methods assume that the load of the indenter and the indentation depth are approximately proportional, that is, that the surface of the test material deforms plastically in response to the indentation of the indenter. Therefore, these methods do not provide an essential solution to the problem of accurately measuring physical properties near the surface of a material, and do not provide an essential solution to the problem of accurately measuring physical properties near the surface of a material.
111 is targeted.

However, recently, it has been desired to further improve the accuracy of the A11j determination of the physical properties near the surface of the material.

In order to meet the demand for higher precision in APj,
It is required to determine the physical properties aPj of only an extremely shallow portion of 1 μm or less on the surface of the material. When indenting with such an extremely shallow partial indenter, the influence of elastic deformation of the material and surface roughness becomes extremely large, and the relationship between the indenter load and the indentation depth becomes complex, resulting in a problem that the accuracy is significantly reduced.

[Problems to be Solved by the Invention] The present invention has been made based on the above circumstances, and provides a method and apparatus for extremely accurately and easily measuring the physical properties of only an extremely shallow portion near the surface of a material. It is.

[Means for Solving the Problems] The measurement method of the present invention involves pushing an indenter into the surface of a test material while changing the indentation load or indentation depth continuously or stepwise, and continuously or stepwise changing the indentation load or indentation depth. The indenter is pulled out while varying the indentation level or stepwise, and the relationship between the load and the indentation depth during the indentation process and the pullout process is measured, and the physical properties near the surface of the test material are calculated from the tllj constant results.

The device of the present invention also includes an indentation mechanism that can continuously or stepwise change the indentation load or indentation depth of the indenter, and an indentation depth detector that detects the indentation depth of the indenter. and a 71PI measurement/control device, which changes the load or indentation depth of the indenter in a predetermined pattern, receives a signal from the indentation depth detector, and receives this signal. This method automatically calculates the physical properties of the surface of the test material.

[Operation] According to the measuring method of the present invention, a component corresponding to plastic deformation and a component corresponding to elastic deformation can be determined from the load-depth relationship in the indenter pushing process and pulling process.

Therefore, the hardness or tensile strength can be accurately determined by eliminating errors from the load-depth relationship in both the pushing process and the pulling process, and the Young's modulus can also be measured. Therefore, it is possible to accurately and easily measure physical properties in an extremely shallow range where elastic deformation and surface roughness have a large effect.

Further, according to the device of the present invention, such changes in indentation load, processing of measurement results, etc. can be automatically performed by the 411j determination/control device, and measurement work can be performed efficiently and accurately. .

[Example] Hereinafter, the present invention will be described in detail with reference to the drawings.

First, a measuring device for carrying out the measuring method of the present invention will be explained with reference to FIGS. 1 and 2.

In order to carry out the above-mentioned measurements, the nj determination device itself must be highly accurate, and various considerations have been taken to achieve this high accuracy.

FIG. 1 schematically shows the entire measuring device.

1 in the figure is a Δpj constant machine, and these all constant machines are housed in an airtight container 2. Further, a measurement/control device 3 is connected to this 1111j constant machine 1, and this measurement/control device 3 is arranged outside the airtight container 2.

A vacuum pump 4 is connected to the airtight container 2 via an on-off valve 5, and is configured to reduce the pressure or evacuate the inside of the airtight container 2. Moreover, 6 is a release valve, and by opening this release valve 6, the inside of this airtight container 2 can be returned to atmospheric pressure. In addition, 7 is a pressure gauge, and the pressure inside this airtight container 2 is displayed by this pressure gauge 7. Note that the inside of this airtight container 2 is replaced with an inert gas as necessary to prevent oxidation of the test material and the like.

The measuring device 1 described above is housed in the airtight container 2 as described above, and the door is closed at regular times to evacuate the airtight container 2 to a vacuum, so there is no air vibration or fluctuation, improving measurement accuracy. do.

A pushing load mechanism 40 is arranged corresponding to the tip of the drive arm section 32 described above. This pushing load mechanism 40
is composed of a solenoid 42 and a plunger 41, the solenoid 42 is attached to the frame 20 side, and the plunger 41 is attached to the drive arm 32.
attached to the side. This solenoid 42 has a fifth
A current is supplied from the load current supply device 43 shown in the figure, and this plunger 41 is attracted to apply torque to this indenter arm 30, and the above-mentioned indenter 36 is pushed into the test material with a pushing load corresponding to the value of this load current. It is configured as follows. Note that the indentation load of this indenter 36 is from 1 mg to several g.
It can be adjusted within the range of.

Moreover, above the tip of the indenter arm 31, an indentation depth detector 50 is arranged.

The indentation depth detector 50 uses an optical displacement meter, detects the displacement of the tip of the indenter arm 31 with an accuracy of, for example, ICL nm, detects the indentation depth of the indenter, and Convert to signal.

Note that this indentation depth detector 50 is configured so that precise positioning can be performed using micrometer heads 51 and 52.

Further, a load detector 60 is attached to the frame side, corresponding to the tip end of the load arm section 33. Further, a protrusion 37 is provided at the tip of the load arm 33 in a position symmetrical to the indenter 36 with respect to the mechanism 70 of the bearing. The protrusion 37 then comes into contact with the contact 62 of the load detector 60 described above. This load detector 60 is capable of detecting the load with an accuracy of mg.
The torque is measured and the above-described indentation load mechanism 40 is calibrated.

Further, FIG. 2 shows the configuration of the measurement/control device 3 described above. A measurement/control circuit 90 is provided in the all measurement/control device 3, and this circuit controls, calibrates, and processes the measurement results of the measuring device 1, as will be explained later. This measurement/control circuit 90 sends a control signal to the load current supply device 53 described above to control the current supplied to the solenoid 42 of the push load mechanism 40,
The suppression load of the indenter 36 is controlled in a predetermined pattern. Further, the load current supplied from this load current supply device 43 is detected by a current detector 94, and after being converted into a digital signal by an A/D converter 93, the J? It is fed back to the J constant/control circuit 90. Further, the signals from the indentation depth detector 50 and the load detector 60 are also amplified by amplifiers 92 and 96, respectively, and converted into digital signals by A/D converters 91 and 95, and then sent to the IIFJ. It is configured to be sent to a control circuit 90.

Further, this measurement/control circuit 90 is programmed to calibrate the indentation load mechanism 40 as follows. First, prior to measurement or periodically, the load detector 60 is moved downward to bring its contactor 62 into contact with the protrusion 37 of the indenter arm 30. Then, when this measurement/control device 3 is activated, this measurement/control circuit 9
A control signal is output from 0 to the load current supply device 43, and the current i supplied from the load current supply device 43 to the solenoid 42 is maintained for a certain period of time Δ[
is increased step by step by a constant Δ1. By energizing this solenoid 42, the above-mentioned indenter arm 3
0, the protrusion 37 presses the contact 62 of the load detector 60, and the load is detected. This protrusion 37
Since the indenter 36 and the bearing described above are arranged in symmetrical positions with respect to the mechanism 70, the load acting on the protrusion 37 is equal to the indentation load actually acting on the indenter 36 when Δ-1 is constant. equal. Then, the load W detected by this load detector 60 is changed by Δ
It increases step by step by W. The above-mentioned al constant/control circuit 90 controls the load current l, 1-n) as shown in FIG. 4 and the load W(1, , 1-n) as shown in FIG.
, , 1) are recorded, and the relationship between these currents and load is approximated by the equation w-8-i+T as shown in FIG. In addition, S.

Each T is a constant. As is clear from FIG. 6, the above-mentioned constant S is the increase in the load T, that is, the pushing load with respect to the increase in the load current i, and this S is the coil sensitivity of the solenoid 42. Therefore, by calculating the values of S and T in this manner, the load current i corresponding to an arbitrary pushing load is determined. Note that the above calculations are performed by the measurement/control circuit 9 mentioned above.
This is done automatically within 0 and automatically stored, and the results are displayed on the display or printed out as required.

Furthermore, this measurement/control circuit 90 is programmed to automatically calibrate the indentation depth detector 50 as described below.

First, prior to calibration, the indenter arm 30 is locked so that it does not rotate. Next, the amount of movement of the indentation depth detector for each step and the number of steps during calibration are input into the measurement/control circuit 90.

Note that such settings may be made in advance.

When the measurement/control device 3 is activated, the output from the depth detector 50 is input to the aPI determination/control circuit 90 and recorded. Next, this all
A signal from the control circuit 90 instructs to perform the next step of calibration.

In accordance with this command, the operator operates the direct-acting micrometer 51 to move the depth detector 50 relative to the indenter arm 30 by a predetermined displacement amount Δ1. Next, the measurement/control circuit 90 receives the output from the depth detector 50 and records it. Hereinafter, in the same manner, the movement amount of the depth detector 50 and its output are calculated as 'l1l
Determine. The relationship between the movement ff1l and the output V measured in this way is as shown in FIG. Based on these characteristics, the constant k is calculated by applying the relationship between l and V to the relational expression V-k·I+M. This constant includes the slope of the straight line shown in FIG. 7, that is, the sensitivity of the indentation depth detector 50. Then, this measurement/control circuit 90 stores this value of k, and uses this sensitivity k during actual measurement to determine the actual indentation depth of the indenter 36 from the output from this indentation depth detector 50. Calculate accurately.

Next, the operation of such a measuring device and such a tP
A 4p1 determination method using a J determination device will be explained.

First, the measurement/control device 3 described above is activated.

The measurement/control circuit 90 controls the load current supply device 43 according to a preset pattern, increases the load current supplied to the solenoid 42 continuously or stepwise, and acts on the indenter 36. Increase the indentation load continuously or stepwise. by this,
This indenter 36 is successively pressed into the surface of the test material. Then, once it has been pushed to the specified depth,
This load current is decreased continuously or stepwise, and the indenter 3
The indentation load acting on 6 is decreased continuously or stepwise. As a result, the indenters 36 are successively pulled out.

In this pushing process and pulling process, the pushing load F of the indenter 36 is changed from the above load current l.
However, the indentation depth d is also measured based on the signal from the indentation depth detector 50, and the relationship between the load F and the indentation depth d is measured continuously or stepwise, and the results are as described above. It is stored in the measurement and control circuit 90. and,
From these measurement results, physical properties such as tensile strength and Young's modulus near the surface of this test material are calculated.

Next, the process of calculating the physical properties of the test material from the above-mentioned 4p1 constant results will be explained by illustrating measurement examples performed on several specific test materials #I.

The test materials used in this exemplary test were aluminum alloy (A2017), phosphor bronze, stainless steel M (SUS
304), silicon with a polished surface, gold in a rolled state, nickel, and platinum.

The indenter used was a pentagonal pyramidal diamond indenter with an angle of 115 degrees to each edge, and the rate of change in the indentation load of this indenter was 10 to 100 mg/sec. Under these conditions, the indenter was pressed into each test material, and after reaching a maximum load of 1000 mg, it was held for 1 second, and then the indenter was pulled out at the same rate of load change as in the pressing process. During this indentation process and withdrawal process, the indentation load F and indentation depth d of the indenter were each continuously measured. The results are shown in FIG.

Since the tip shape of this indenter is known in advance, the dimensions of the indentation that would have been formed by this indenter can be calculated from the indentation depth d of this indenter, and the apparent Vickers hardness of these test materials can be calculated using the conventional method. When H is calculated, H-F/S -0,03784·F/d2 (1) is calculated.

FIG. 9 shows the results of calculating the hardness H of each test material using such a conventional method. As is clear from this result, there is a large error in the apparent hardness in a shallow region as illustrated. In particular, the error becomes extremely large in the region of 100 Bm or less. This is because the tip of the indenter is not necessarily geometrically sharp, the elastic deformation of the test material precedes the initial contact, and the surface roughness of the test material. Therefore, conventional methods cannot accurately grasp the physical properties of materials in such a shallow range.

Therefore, in the present invention, the relationship between the load F and the indentation depth d in the indentation area in such a shallow area, that is, the area where the elastic deformation of the test material and the surface roughness are large, is expressed as F;A-d+B-d2 =-( 2) However, A and B are constants; approximate to the following formula. Note that A and B are constants.

The first term in equation (2) corresponds to the elastic deformation and surface roughness of the material, and the second term corresponds to the plastic deformation of the test material. This equation (2) holds true when plastic deformation and elastic deformation of the material coexist. Since this plastic deformation occurs when the indentation load of the indenter and the yield stress of the material are balanced, the above constant B corresponds to the Vickers hardness Hv of this material.

When the above equation (2) is divided by d, it becomes F/d=A+Bd (3). 7ip1 actually measured for each of the above test materials
10 and 11 if the results are illustrated in terms of the relationship between F/d and d as shown in equation (3). This first
As is clear from FIG. 0 and FIG. 11, the relationship between F/d and d maintains an extremely linear relationship up to a region of 1100n or less. As schematically shown in FIG. 12, the slope in this indentation process, that is, B corresponds to the Pickchus hardness. In addition, the tensile strength σB of the material
and Vickers hardness Hv, Hv=0.3177
Since there is a relationship of B (MP a) − (4),
The tensile strength can be easily calculated from this Vickers hardness. Incidentally, FIG. 13 shows the B and HvO values of each test material actually measured as described above, and it is clear that they correspond accurately to the theoretical values.

Further, in the process of pulling out the indenter, it is considered that the recovery force of the elastic deformation of the indented portion and the load of the indenter are balanced. Unlike plastic deformation, this elastically deformed part is considered to be elastically deformed over a wider range than the part directly in contact with the indenter. However, in any case, the area S of the elastically deformed part is proportional to the area in direct contact with the indenter, that is, d2, and the depth of the elastically deformed part [is proportional to the indentation depth d of the indenter. It is considered to be proportional. In addition, at the beginning of the drawing process, it is thought that the indenter is in full contact with the test material.
If the maximum indentation load is F□, the maximum indentation depth is d7, and the Young's modulus of the material is E, then (F-F,)/SzE (d-
d,,)/1(5). Here, if 5-ad-'t-βd1, the above equation (5) becomes F / d, za /β-E - (dd,) ten F
ffi/d.

...(6) becomes. Furthermore, at the beginning of the drawing process, dad, so the above equation (6) can be expressed as D-α/β·E, F/d-D (d-d-) 10F-/d, .

...(7) becomes. Also in the actual measurement results shown in FIGS. 10 and 11, the relationship expressed by equation (7) is extremely close to a straight line. Therefore, from this slope or D, the Young's modulus E of this material
is required.

In addition, Fig. 14 shows the relationship between D and Young's modulus E calculated from the results of actual 1llllll determination, and as is clear from this figure, the actual Δ-j constant value corresponds exactly to the theoretical value. There is. The relationship between D and E is D;==-3,
61.E (MP a) - (8).

As described above, according to the method of the present invention, physical properties can be measured extremely accurately even in an extremely shallow region of 1100 nm or less near the surface of a test material.

Note that the present invention is not limited to the above embodiments.

For example, the 71p] determination method of the present invention does not necessarily need to be carried out using the apparatus described above.

Further, the apparatus of the present invention is not necessarily limited to the above-described embodiments, and various modifications can be made as necessary.

[Effects] As described above, according to the measuring method of the present invention, it is possible to accurately and easily determine the physical properties of an extremely shallow portion near the material surface, which could not be determined using conventional methods. Further, the apparatus of the present invention can automatically and efficiently carry out such a measurement method using such a measurement/control device.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of the entire device of the present invention, Fig. 2 is a schematic diagram of the measurement and control device, Fig. 3 is a diagram showing changes in the supplied load current, and Fig. 4 is a current detector. Detected current □
Figure 5 is a diagram showing the state of the load detected by the load detector, Figure 6 is a diagram showing the relationship between load current and load, Figure 7 is the diagram showing the relationship between the load detector and the load detector. Figure 8 is a diagram showing the relationship between load and indentation depth for various test materials, Figure 9 is a diagram showing the apparent hardness of each test material, 10 and 11 are diagrams showing the relationship between F/d(!:d) of various test materials, and FIG. 12 is a diagram schematically explaining the relationship in FIGS. 10 and 11. Fig. 13 is a diagram showing the relationship between the hardness of various test materials and B, and Fig. 14 is a diagram showing the relationship between Young's modulus and D of various materials.1...4a1 fixed machine, 2... Airtight container, 3... A1
11 constant/control device, 4... vacuum pump, 30... indenter arm, 40... indentation load mechanism, 50... indentation depth detector, 60... load detector, 70... bearing is a mechanism.

Claims (7)

[Claims] (1) A method of measuring the physical properties of the surface of a test material by pushing an indenter into the surface of the test material, in which the indenter is pressed onto the surface of the test material while changing the indentation load F or the indentation depth applied to the indenter. In this indentation process, the relationship between the indentation load F and the indentation depth d is continuously or stepwise measured, and the indentation load F or the indentation depth applied to the indenter is varied. a process of pulling out this indenter from the surface of the test material while and a step of calculating physical properties of the surface of the test material from the relationship between the indentation depth d and the indentation depth d. (2) The process of calculating the physical properties of the above test material is to calculate the relationship between the indentation load F and the indentation depth d in the indenter indentation process using the following formula F/d≒A+B・d However, A, The measuring method according to claim 1, characterized in that the Vickers hardness Hv or the surface tensile strength σ_B of the test material is determined from the constant B by approximating the following relational expression: B is a constant. (3) The process of calculating the physical properties of the above test material is to calculate the relationship between the indentation load F and the indentation depth d in the indenter withdrawal process using the following formula F/d_m≒F/d≒D(
d-d_m)+F_m/d_m However, F_m is the indentation load at the maximum indentation, d_m is the indentation depth at the maximum indentation, and D is a constant. The measuring method according to claim 1, characterized in that the ratio E is determined. (4) A device for measuring the physical properties of the surface of a test material by pushing an indenter into the surface of the test material, which comprises: an indenter having a predetermined tip shape; and an indentation load applied to the indenter that changes continuously or stepwise. an indentation load mechanism that can apply an indentation load, an indentation depth detector that detects the indentation depth of this indenter, and an indentation load mechanism that controls the above indentation load mechanism to change the indentation load or indentation depth that acts on the indenter. While pushing the indenter into the surface of the test material, the indenter is pulled out while changing the indentation load or indentation depth, and receives the signal from the indentation depth detector, and then the indentation load is increased. and a measurement/control device that calculates the physical properties of the surface of the test material from the relationship between the indentation depth of the indenter and the indentation depth of the indenter. (5) The indentation load mechanism described above includes a solenoid, and the measurement/control device changes the indentation load acting on the indenter by controlling the current supplied to the solenoid. The measuring device according to claim 4. (6) The above measurement/control device calculates the relationship between the indentation load F and the indentation depth d in the indenter indentation process using the following formula F/d≒A+B.
d, where A and B are each constant; Approximate to the following relational expression, and from this constant B, the Vickers hardness Hv or tensile strength σ_B of the surface of the test material is determined. How to measure. (7) The above measurement/control device calculates the relationship between the above indentation load F and the indentation depth d in the process of pulling out the indenter using the following formula F/d_m≒F/d
≒D(d-d_m)+F_m/d_m However, F_m is the indentation load at the maximum indentation, d_m is the indentation depth at the maximum indentation, and D is a constant. 2. The measuring method according to claim 1, wherein the Young's modulus E of a material is determined.