Improvements in magnetic performance and sintered density of metal injection-molded soft magnetic alloy by hot isostatic pressing

• High-performance Fe-79%Ni-4%Mo alloy was produced by metal injection molding.
• Maximum permeability was sensitive to stress and closely related to grain size.
• The sintering parameters of Fe-79%Ni-4%Mo alloy were optimized.

Metal injection molding (MIM) is a process that has the predominance in the economical mass production of minisize, complex shaped soft magnetic parts. However, not full dense materials could have their density dependent properties as magnetic induction decreases, and also generated microstructure can be affected, showing large pores, that could act as domain-wall barriers reducing soft magnetic performance. This study overcame this problem and obtained high magnetic property and full density Fe-79%Ni-4%Mo alloy by MIM, hot isostatic pressing and subsequent heat treatment. The maximum permeability, saturation induction and coercive force are 210,000, 0.862 T and 0.95 A/m, respectively. The relationships between processing parameters, density, stress, microstructure and magnetic properties were investigated. The results revealed that maximum permeability was more sensitive to stress and magnetic performance was strongly influenced by density and microstructure.