The preparation method of vacuum hotpressing self-formed from reaction titanium matrix composite
Technical field:
The present invention relates to a kind of preparation method of titanium matrix composite, being specifically related to a kind of is the preparation method that titanium boride whisker and titanium carbide granule strengthen titanium matrix composite by titanium and boron carbide self-formed from reaction enhancing body.
Background technology:
Metal-base composites owing to characteristic with metal, also have the combination property that height ratio is strong, height ratio is firm, heat-resisting, wear-resisting and be subjected to extensive attention.In these composites, titanium or titanium alloy has characteristics such as light specific gravity, corrosion-resistant, resistance to oxidation intensity height, is a kind of alloy that can use under 450~650 ℃ of conditions and being favored.Titanium matrix composite has better resistance to elevated temperatures than Al, Mg based composites, has caused people's attention.Titanium matrix composite (TMCs) becomes the candidate material of superelevation velocity of sound aerospace vehicle and advanced aero-engine of future generation.TMCs is broadly divided into fiber and particle strengthens two classes.Fiber reinforcement TMCs is because the manufacturing process complexity costs an arm and a leg, and development is restricted, and only is used for Ministry of Aero-Space Industry's door on a small quantity.Granule intensified titanium-base compound material is compared with the fiber reinforcement titanium matrix composite, particle wild phase cost with use is low, and the designability of performance and function is strong, manufacturing process technology relatively economical simple possible, prepared material has isotropism, can obtain advantages such as near-net-shape part.The adding of particle wild phase has improved the normal temperature of titanium alloy and high temperature effectively than elastic modelling quantity, specific strength and creep resistance.But the plasticity of this titanium alloy material, toughness descend.
Summary of the invention:
The preparation method who the purpose of this invention is to provide a kind of vacuum hotpressing self-formed from reaction titanium matrix composite, this method is reduced to one with the preparation technology of fiber reinforcement titanium matrix composite and the preparation technology of granule intensified titanium-base compound material, not only fiber reinforcement titanium matrix composite complicated process of preparation, expensive shortcoming have been overcome but also have solved the deficiency that granule intensified titanium-base compound material plasticity, toughness descend, have method simple, make easily, the titanium matrix composite of making is fine and close more, strengthen the characteristics that body is evenly distributed, quality is high.Method of the present invention the steps include: that (1) mix powder: at first with Ti powder and B
4The C powder prepares by weight puts into jar, adds steel ball in jar again, and jar sealing back is mixed on planetary ball mill, and incorporation time is 10-14 hour; (2) vacuum-sintering: the powder that the mixes graphite jig of packing into is colded pressing, carry out vacuum heating-press sintering again, before the sintering under 500-800 ℃ of condition degasification 0.4-1 hour, carry out sintering then, sintering temperature is 1000-1250 ℃, and sintering pressure is 15-25MPa, and sintering time is 0.4-1 hour; (3) hot extrusion: with the separately heating of the composite behind the sintering and extrusion die, composite is heated to 800-1400 ℃ separately, and being incubated and putting into holding temperature after one hour is that 650 ℃ extrusion die pushes, and extrusion ratio is 16: 1, and extrusion molding gets final product.Described Ti powder and B
4The weight ratio of C powder is 160: 1; Described Ti powder and B
4The weight ratio of C is 100: 1; Described Ti powder and B
4The weight ratio of C powder is 50: 1; The granularity of described Ti powder is 1-50 μ m; Described B
4The granularity of C powder is 1-10 μ m; The diameter of described steel ball is 5-20mm; Described steel ball and Ti powder and B
4The ratio of grinding media to material of C powder is 1: 1; The present invention is reduced to one with the preparation technology of fiber reinforcement titanium matrix composite and the preparation technology of granule intensified titanium-base compound material, not only fiber reinforcement titanium matrix composite complicated process of preparation, expensive shortcoming have been overcome but also have solved the deficiency that granule intensified titanium-base compound material plasticity, toughness descend, have method simple, make easily, the titanium matrix composite of making is fine and close more, strengthen the advantage that body is evenly distributed, quality is high.Thereby improved its serviceability as structural material.
Description of drawings:
Fig. 1 is test Ti-B
4The DSC curve map of C mixture.
The specific embodiment:
Present embodiment is achieved in that (1) mix powder: at first with Ti powder and B
4The C powder prepares by weight puts into jar, adds steel ball in jar again, and jar sealing back is mixed on planetary ball mill, and incorporation time is 10-14 hour; Best mixing time is 12 hours, (2) vacuum-sintering: the powder that the mixes graphite jig of packing into is colded pressing, carry out vacuum heating-press sintering again, before the sintering under 500-800 ℃ of condition degasification 0.4-1 hour, best degasification temperature was 800 ℃; Carry out sintering then, sintering temperature is 1000-1250 ℃, and optimal sintering temperature is 1200 ℃; Sintering pressure is 15-25MPa, and sintering time is 0.4-1 hour; (3) hot extrusion: with composite behind the sintering and separately heating of extrusion die, composite is heated to 800-1400 ℃ separately, and optimal heat extruding heating-up temperature is 1150 ℃; Being incubated and putting into holding temperature after one hour is that 650 ℃ extrusion die pushes, and extrusion ratio is 16: 1, and extrusion molding gets final product.Described Ti powder and B
4The weight ratio of C powder is 160: 1; Described Ti powder and B
4The weight ratio of C is 100: 1; Described Ti powder and B
4The weight ratio of C powder is 50: 1; The granularity of described Ti powder is 1-50 μ m; Described B
4The granularity of C powder is 1-10 μ m; The diameter of described steel ball is 5-20mm; Described steel ball and Ti powder and B
4The ratio of grinding media to material of C powder is 1: 1.
In order to determine B
4The reaction optimum temperature of C and Ti has been tested Ti-B
4The DSC curve (see figure 1) of C mixture.As can be seen, Ti and B
4The reaction of C heat release occurs during since 900 ℃, illustrates that metal Ti begins and B
4Chemical reaction takes place in C.Along with the rising of temperature, it is maximum that exothermic peak to 1000 ℃ reaches, and can think Ti and B this moment
4The C reaction is the most violent, to 1250 ℃ of end.In order to make Ti and B
4C powder complete reaction, sintering temperature are chosen as 1200 ℃.The TiB whisker evenly generates in the titanium matrix, and diameter of whiskers has only about 0.075~0.3 μ m, and length is approximately 0.3~30 μ m.The TiC particle also evenly generates in the titanium matrix.Graphite jig is adopted in hot pressing.The extrusion die of using during hot extrusion, recipient adopts the 3Cr2W8V material, and the GCr15 material is adopted on die, pressure head and chassis.Because plasticity is relatively poor at normal temperatures, fragility is big for titanium matrix composite, be not easy to carry out plastic working, so thermal deformation is one of main mode of texturing of discontinuous enhancing titanium matrix composite.Optimal heat extrusion process: 1150 ℃, be incubated 1 hour, extrusion ratio 16: 1.Titanium is a close-packed hexagonal structure when being lower than 882 ℃, and slip system is fewer, and deformation ratio is difficulty.When hot extrusion, material is heated to 1150 ℃, titanium is in body-centered cubic structure, and slip system is many, and the plastic deformation ratio is easier to.If but temperature is too high, crystal grain is grown up easily, therefore, adopts suitable extrusion temperature, and is most important for the material for preparing.The density of sintered state material increases and reduces along with the volume fraction that strengthens body, and this is that the interfacial area that strengthens body and matrix increases because along with the volume fraction that strengthens body increases, thereby interface contact " loose " degree is increased.After hot extrusion, the porosity of material reduces, basically near solid density.Suitable hot extrusion technique parameter can obtain more satisfactory material.By the extruding attitude is mixed reinforced composite along the direction of extrusion (vertically) with perpendicular to the direction of extrusion microscopic examination of (laterally), after high temperature crimp, the evident characteristic of its institutional framework is that whisker has produced aligning along the direction of extrusion.The composite of sintered state is behind hot extrusion deformation, and material is fine and close more, strengthens body and is evenly distributed, thereby can obtain better institutional framework, has improved its serviceability as structural material.Result of study shows, the complete and B of Ti powder
4C reaction generates TiC and TiB, and the whisker of short fiber shape is TiB, is TiC and wait the axle shape or axle shape particle such as be similar to.By extrusion die reasonable in design and suitable extrusion process, can successfully squeeze out high-quality titanium matrix composite.