Investigation of a Ni-38Mo binary alloy fabrication by mechanical alloying and spark plasma sintering

The present work investigated a Ni-38Mo binary alloy with a specific interest in Ni solid solution and Ni-Mo intermetallic phases. To this end, a homogeneous Ni-Mo alloy powder obtained via mechanical alloying was consolidated by spark plasma sintering (SPS). The main constitutive phases post-SPS were a Ni(Mo) solid solution and the delta-NiMo intermetallic phase. Subsequent heat treatment at 1200 degrees C caused an increase in microhardness to 985 HV, while an additional aging process at lower temperatures caused a softening effect associated with the presence of beta-Ni4Mo. Microstructural observation suggested that heat treatment at 1200 degrees C was responsible for the promotion of delta-NiMo in favor of mechanical properties and the stability of such intermetallic phase, which prevented massive phase transformation in subsequent heating. Thus, the present work may lay the groundwork for a multipurpose Ni-Mo alloy having attractive structural and functional properties.