Microstructure and mechanical properties of CxHf0.25NbTaW0.5 refractory high-entropy alloys at room and high temperatures

• 作者: Shiyu Wu Dongxu Qiao Haitao Zhang Junwei Miao Hongliang Zhao Jun Wang Yiping Lu Tongmin Wang Tingju Li
• 来源期刊: 材料科学技术（英文版）
• 年，卷（期）: 2022,（2）
• 页码范围: 229-238
• 页数: 10页
• 语种: 英文

摘要

The microstructure and mechanical properties of as-cast and isothermally annealed CxHf0.25NbTaW0.5(x=0,0.05,0.15,0.25)refractory high-entropy alloys(RHEAs)were studied.Both the as-cast and annealed RHEAs consisted of disordered body-centered cubic solid solution phase and metal carbide(MC)phase with a face-centered cubic crystal structure(Fm-3m space group).The primary carbides were enriched with Hf and C elements and tended to form lamellar eutectic-like microstructure in the interdendrites.The lamellar eutectic-like structure in the interdendrites would be formed from the decomposition of sub-carbide M2C under the influence of Hf element.After isothermal annealing,slatted carbides were precipitated on the matrix,and the distribution became more uniform with high C content.The forma-tion of carbides strongly influenced the mechanical properties both at room and high temperatures.The yield strength values of C0.25Hf0.25NbTaW0.5 RHEA at 1473 and 1673 K were 792 and 749 MPa,respec-tively.The result had exceeded the high temperature mechanical properties of currently known RHEAs.Moreover,this RHEA exhibited high-temperature performance stability and excellent plasticity,exceeding 30 and 50％at room and elevated temperatures(above 1273 K),respectively.During thermal deformation,carbon-containing RHEAs obtained more severe work hardening than that of ACHO RHEAs,and required greater dynamic recrystallization to achieve the dynamic equilibrium.