Study On Microstructure Evolution And Mechanical Properties Of Tizrv Three-Component Alloy

Due to its good microstructure stability and hysteresis diffusion effect,multi-principal component alloys have attracted a lot of attention.Due to its low density,high specific strength,good corrosion resistance and elastic modulus close to human bone,Ti base multi-component alloy has great development potential in medical treatment and daily life.In this paper,three kinds of alloys were designed by calculating molybdenum equivalent,electron concentration,Bo,Md value and complete solid solution criterion.The nominal components were Ti-25Zr-25V,Ti-25Zr-25V-3Al and Ti-25Zr-15V-6Nb-3Mo-3Al.The microstructure and mechanical properties of the three alloys were systematically studied in the as-cast condition,cold rolling and heat treatment,so as to provide a basic reference for further research and development of Ti-Zr-V multi-principal component alloys.The experimental results show that:（1）The tensile yield strength of Ti-25Zr-25V alloy is 620MPa,and the total elongation can reach 14%.Good cold forming,cold rolling and pressing capacity up to 75%and boundless crack.After recrystallization annealing and aging treatment at 850℃/30min+500℃/12h,the grain size was 20～50μm,and there was phase precipitation in the structure.After aging,the yield strength of the alloy reached 720MPa and the total elongation remained 10.2%.（2）The as-cast microstructure of Ti-25Zr-25V-3Al alloy is composed of a single phase.After heat preservation and quenching at 800℃,the alloy underwent martensitic transformation.As-cast tensile yield strength of the alloy was 940MPa and the total elongation was 11.8%.Al3Zr5 was precipitated by recrystallization annealing after cold rolling.The formation of the compound could be avoided after recrystallization at 1100℃/1min.After recrystallization,the tensile yield strength was 950MPa and the total elongation was 18.8%.After aging,a large amount of Al3Zr5 was precipitated out.After aging at 300℃/12h,the alloy strength was 1120MPa and the elongation at break was 2%.After aging at 500℃/1h,the alloy strength was 970MPa and the elongation at break was 7%.The precipitation temperature of Al3Zrs is between 300℃ and 1100℃.With the extension of the holding time,it changes from granular to long strip precipitation,which has a great influence on the plasticity of the alloy.In addition,after direct aging after cold rolling,the alloy reached the peak of aging at 400℃/6h,the hardness was 570HV,and the tensile yield strength was 1750MPa.（3）The as-cast state of Ti-25Zr-15V-6Nb-3Mo-3Al alloy consists of a single phase.After quenching at 800℃,the alloy underwent martensitic transformation.The as-cast tensile yield strength of the alloy was 740MPa and the total elongation was 10.8%.The recrystallization annealing grain size at 1100℃/1min was 20～50μm,the tensile yield strength was 805MPa,and the total elongation was 19%.After aging,Al3Zr5,the second phase compound,was precipitated.After aging treatment at 300℃/12h,the tensile yield strength of the alloy was 940MPa and the total elongation was 12.5%.After aging treatment at 400℃/4h,the tensile yield strength of the alloy was 1,130mpa and the elongation at break was 3%.Compared with Ti-25Zr-25V-3Al alloy,the precipitation ability of Al3Zr5 compound in this alloy is relatively weak.