Tantalum alloy is attractive in the aspects of room temperature plasticity, formability, corrosion resistance and melting point, but its poor fatigue strength has become the main obstacle to its application as high temperature structural materials. At the same time, when the temperature exceeds 1100℃, the creep resistance of tantalum alloy decreases significantly. Tantalum alloy with high alloy concentration can be formed by adding W, Hf, Zr and other alloying elements to tantalum, its high temperature mechanical properties are significantly improved, and the processing performance is good, so it is used as high temperature structural materials. Although the high temperature mechanical properties and fatigue strength of tantalum alloy can be improved to some extent by adding alloying, the mechanical properties cannot be greatly improved. Therefore, it is necessary to overcome the shortcomings of single-phase tantalum alloy through the second phase dispersion strengthening, and develop multiphase tantalum alloy strengthened by ceramic phase. Through alloying and process control, the ceramic phase tiny particles are uniformly dispersed on the tantalum matrix, so that its mechanical properties at room temperature, high temperature mechanical properties and fatigue strength are significantly improved, while the room temperature plasticity of the alloy is not significantly reduced.
Composites can be prepared by a combustion synthesis process. The steps of the process consist of igniting a mixture consisting of at least one element or a mixture of two or more of them selected from titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, aluminum, and silicon, at least one boron-containing compound or a mixture of them selected from boron nitride, boron carbide, and a certain number of metals capable of reducing the ignition temperature. The metal is selected from one of the metals of iron, cobalt, nickel, copper, aluminum, silicon, palladium, platinum, silver, gold, ruthenium, rhodium, osmium and iridium or a mixture of two or more of them, provided that at least one of the said elements is different from at least one of the said metals. This process allows a higher degree of control over the microstructure of the product and requires relatively low pressure to obtain the high density of the composite. Dense products with high density and fine-grained microstructure can be obtained by applying mechanical pressure during combustion synthesis. The composite material has high hardness, toughness, strength, wear resistance and fracture resistance.
The purpose is to provide a Ta-Hf-Zr-ZrB2 alloy bar and a preparation method thereof. The method provides a method of hot isostatic pressing sintering to prepare Ta-Hf-Zr-ZrB2 alloy bar. The Ta-Hf-Zr-ZrB2 alloy bar has good high temperature oxidation resistance, room temperature plasticity and tensile strength. Excellent fatigue strength, high temperature strength and superplasticity, can be used for high temperature structural parts, suitable for bars and so on.
