摘要
The refractory high entropy alloys(RHEAs)containing disordered body-centered cubic(BCC)and ordered BCC(B2)structures often exhibit high strength but low ductility at room temperature,even in the compressive tests.In this study,(Ta_(25-x)Nb_(25)Zr_(25)Ti_(25+x))95Al_(5)(x=0,5,10)RHEAs are fabricated to investigate the compositional dependence of the microstructures and mechanical properties.All the three alloys exhibit a single BCC structure at the as-cast and solution-treated states,while the basket weave-like microstructures consisting of cuboidal and strip-like phases are formed after aging at 600°C.The microstructure of the aged alloys is sensitive to the compositions:only disordered BCC1+BCC2 dual phases are observed in the(Ta_(25)Nb_(25)Zr_(25)Ti_(25))_(95)Al_(5)alloy;additional B2 phases are formed by replacing 5 at%Ta with Ti;a complex microstructure containing BCC1+BCC2+B2+Omega phases are identified in the(Ta_(15)Nb_(25)Zr_(25)Ti_(35))_(95)Al_(5)alloy.Although replacing Ta with Ti results in a reduction of compressive yield strength from 1762 to 1243 MPa,the fracture strain is greatly enhanced from 7.3 to 44.3%,indicating that the strength-ductility balance can be tuned to a large extent in this RHEA system.
基金
financially supported by the National Natural Science Foundation of China (Grant No. 11905008)
