微量Ni对MgNi合金组织与性能的影响

Effect of Trace Ni on Microstructure and Properties of Mg-Ni Alloys

在铸态情况下,研究了添加微量Ni对MgNi合金的微观组织、力学性能、硬度及断裂方式的影响.结果表明,纯Mg的组织主要为α相,MgNi系列合金MgNi0.28,MgNi0.99,MgNi1.54合金除了α固溶体外,还存在γ相和Ni相.纯Mg的晶粒粗大,加入Ni后,晶粒得到细化,大小趋向均匀.当添加少量Ni时,合金的抗拉强度显著增加;但当Ni含量超过0.28%时,抗拉强度增加不明显.随Ni含量的增加,MgNi合金的延伸率、硬度先增大后减小;MgNi合金的断裂方式由解理断裂向沿晶断裂方向发展.

Effects of Ni additions on the microstructure and mechanical properties as well as fracture mode of casting Mg-Ni alloys are investigated in this study.The results indicate that pure Mg is mainly composed of α phase,and that MgNi0.28,MgNi0.99,MgNi1.54 alloys have γ and Ni phase besides α solid solution.The grain size of pure Mg is coarse,but it becomes thin and the size has a trend to be homogeneous after addition of Ni.The ultimate tensile strength increases remarkably when adding a small amount of Ni.However,the ultimate tensile strength doesn＇t increase obviously when the content of Ni exceeds 0.28%.With the increase of Ni content,the elongation and hardness increase first and then decrease.The fracture mode of MgNi alloys changes from cleavage fracture to intergranular fracture.