摘要
In this study,non-equiatomic Fe_(70)Co_(7.5)Cr_(7.5)Ni_(7.5)V_(7.5) medium-entropy alloys(MEAs)with different carbon contents were prepared via mechanical ball-milling,cold pressing and vacuum sintering.The microstructural evolution,mechanical properties and wear resistance of the MEAs were investigated.Fe_(70)Co_(7.5)Cr_(7.5)Ni_(7.5)V_(7.5) exhibited a bodycentered cubic(bcc)structure withσphase precipitation.After adding 4 at%and 8 at%carbon,the phase composition of the alloys was transformed to bcc+MC+σand bcc+MC+M_(23)C_(6),respectively.The mechanical properties and wear resistance were observed to be significantly enhanced by the formation of carbides.Increasing the carbon content,the corresponding bending strength and hardness increased from 1520 to 3245 MPa and HRC 57.2 to HRC 61.4,respectively.Further,the dominant wear mechanism changed from the adhesion wear to the abrasion wear.Owing to the evenly distributed carbides and precipitated nanocarbides,Fe_(64.4)Co_(6.9)Cr_(6.9)Ni_(6.9)V_(6.9)C_(8) revealed an extremely low specific wear rate of 1.3×10^(−6) mm_(2)/(N·m)under a load of 10 N.
本文采用机械球磨、冷压成型和真空烧结法制备了碳含量不同的非等原子比Fe_(70)Co_(7.5)Cr_(7.5)Ni_(7.5)V_(7.5)中熵合金,并对合金的组织演变、力学性能和耐磨损性能进行了研究。Fe_(70)Co_(7.5)Cr_(7.5)Ni_(7.5)V_(7.5)合金以体心立方结构(bcc)为基且内部有σ析出相。加入4 at%和8 at%的碳后,合金相组成分别转变成bcc+MC+σ和bcc+MC+M_(23)C_(6)。合金力学性能和耐磨损性能随基体内碳化物的增加而显著提升。随碳含量的提高,合金的抗弯强度和硬度分别从1520 MPa和HRC 57.2提高到3245 MPa和HRC 61.4。并且,合金的主导磨损机制从黏着磨损转变为磨粒磨损。由于均匀分布的微米级碳化物和析出的纳米级碳化物,Fe_(64.4)Co_(6.9)Cr_(6.9)Ni_(6.9)V_(6.9)C_(8)在10 N的载荷下具有极低磨损率,为1.3×10^(-6)mm^(2)/(N·m)。
基金
Project(2016YFB0700300)supported by the National Key Research and Development Program of China。
