Microstructure and mechanical properties of a low activation cast WTaHfTiZr refractory high-entropy alloy

In the face of the requirement that nuclear fusion reactor materials exhibit more excellent thermal,mechanical and physical properties,a novel refractory highentropy alloy,WTaHfTiZr was proposed.The constituent elements were selected in consideration of low activation,high melting point and high thermostability.The alloys were prepared by arc melting.The as-cast alloy shows a dendrite microstructure with two disordered BCC phases,which caused by the preferential nucleation of W and Ta with much higher melting points during solidification.It exhibits a high compressive yield strength of 1,900 MPa and fracture strain of 8.1% at room temperature,and its yield strengths are up to 612 MPa at 700 ℃ and 203 MPa at 1,000 ℃,respectively.The high strengths are attributed mainly to solid solution strengthening and second phase strengthening.This alloy shows great promise as one of the next-generation nuclear fusion reactor materials.