Design of Laves-phase-packed spheres in wear-resistant Cu alloy by controlled liquid immiscibility

Abstract

The designed liquid immiscibility of Cu-Ni-Fe-Mo-Si alloy led to separation of the spherical second liquid in the Cu-rich liquid, which solidified into coarse hard grains packed with Laves phase. The coarseness of hard grains was controlled not only by the repulsive interactions in Cu–Fe and Cu–Mo system, but also the refining effect of Ni and Si. CALPHAD analysis of the multicomponent system confirmed the correlation of the calculated fraction of the separated liquid with the observed grain dimensions. It also provided a powerful prediction of the precipitates constituting the hard grains. Almost all of the alloying effects on the observed microstructures were successfully interpreted based on equilibrium immiscibility calculations, although a reason for the refining of spheres with increasing Si remains unclear.