Abstract
Ti with 30 mass% Nb + 10 mass% Ta + 5 mass% Zr, that is, Ti-30Nb-10Ta-5Zr, which is simplified chemical composition of Ti-29Nb-13Ta-4.6Zr, was decided as basic composition to investigate the effect of alloying element Nb on mechanical properties of Ti-Nb-Ta-Zr system alloys in this study. Ti-Nb-10Ta-5Zr alloys with different Nb contents were fabricated by blended elemental powder metallurgy method. The elastic modulus and tensile properties of the designed alloys were investigated. While, the microstructures of these alloys were observed by using an optical microscope and a transmission electro microscope. The alloy with 0 mass% Nb shows a microstructure consisting of single α phase. Precipitation of ω phase and α'' phase are observed in the alloys containing of 10 mass% and 15 mass% Nb. The alloys containing of over 20 mass% Nb shows ω phase precipitated in β phase. The alloys containing of over 30 mass% Nb show single β phase. Variation of microstructure, elastic modulus, elongation, reduction of area, 0.2% proof stress and tensile strength become smaller in the alloys containing of over 35 mass% Nb. The alloy containing of 30 mass% Nb shows the lowest elastic modulus. A deformation mechanism that is different from the general slip deformation of titanium alloy appears in the alloy containing of Nb between 20 mass% and 30 mass%.
