热处理及轧制过程中NiPt5合金微观组织及磁性能演变

Microstructure and magnetic properties evolution of NiPt5 alloy during heat treatment and rolling

采用光学显微镜观测、透磁率测试分析、模拟计算等方法,研究NiPt5合金的微观组织随热处理温度的演变规律及热处理条件和轧制变形量对磁性能的影响。结表果明,NiPt5合金经过开坯和变形,750℃×2 h热处理时再结晶不完全,当温度达到900℃后,晶粒尺寸细小且分布均匀。当NiPt5合金发生回复及再结晶以后,其平均透磁率较轧制态有明显降低,并在此阶段内波动不大,当完全再结晶及晶粒长大以后,平均透磁率进一步降低。结合模拟轧制变形过程中的内应力变化,发现随着板坯变形量增大,其内部应力增加,位错密度增加,畴壁移动阻碍增多,平均透磁率显著提升,之后随着变形量增加,应力和位错密度达到饱和,平均透磁率趋于平稳。随着变形量增加,内部应力增大且分布不均匀,透磁率极差呈增大趋势。

Microstructure evolution of NiPt5 alloy at different heat treatment temperatures,and the influence of heat treatment conditions and different deformation amounts on magnetic properties were studied by means of optical microscope,magnetic permeability testing and simulation calculations.The results show that the recrystallization of the NiPt5 alloy is not complete after forging and rolling and then heat treatment at 750℃for 2 h.When the temperature reaches 900℃,the grain size is fine and evenly distributed.The magnetic permeability of the NiPt5 alloy decreases significantly compared with that of the rolled state during the recovery and recrystallization process,with little fluctuation in this stage.The magnetic permeability decreases further at the stage of complete recrystallization and grain growth.Combined with the stress change simulation during rolling deformation,it is found that with the increase of deformation amount,the internal stress,the dislocation density and the barrier of domain walls movements increase,and the magnetic permeability increases significantly.Then with the increase of deformation amount,the stress and dislocation density reach saturation,the magnetic permeability tends to be stable,and the magnetic permeability volatility increases with the increase of deformation amount,but the internal stress distribution is uneven,showing an increasing trend.