Abstract: 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.

Key words: sputtering target, NiPt5 alloy, microstructure, rolling deformation, magnetic properties