Microstructure and mechanical properties of Ti-Cr-Nb-V-Zr refractory high entropy alloys with high specific yield strength
Ti47-xCr18Nb23V12Zrx(x=0,4,8 and 12 at％)refractory high entropy alloys(RHEAs)were prepared by vacuum arc melting method,and then the as-cast alloys were subsequently homogenized at 1200 ℃ for 12 h.Phase constitution,microstructure and mechanical properties of the as-cast and homogenized alloys were investigated by means of X-ray diffraction(XRD),scanning electron microscopy(SEM),universal mechanical testing machine and microhardness tester.The results show that the addition of Zr element causes the precipitation of C15-structured Cr2(Ti,Nb,V,Zr)-Laves phase between dendrites in the as-cast alloys.The increase of Zr element content enhances the compressive yield strength and hardness of the alloys,but reduces its plasticity.The homogenization heat treatment does not change the phase composition of the alloys,but significantly changes the microstructure and morphology of the alloys,greatly increasing the volume fraction of precipitates.After homogenization heat treatment,the strength and hardness of the alloys are reduced,but the plasticity is improved.Among them,the compressive plasticity of the Ti43Cr18Nb23V12Zr4 alloy increases from 29％in the as-cast to over 50％after homogenization heat treatment,with a yield strength of 1110 MPa and a specific yield strength of up to 180 MPa ·cm3·g-1,showing excellent strength plasticity matching.In addition,due to the fine dispersed Laves phase,the yield strength and plasticity of the Ti39Cr18Nb23V12Zr8 alloy after homogenization heat treatment have been slightly enhanced.
refractory high entropy alloyhomogenizing heat treatmentmicrostructuremechanical propertyhigh specific yield strength
NETL
NSTL
万方数据
