Dependence of microhardness on solidification processing parameters and dendritic spacing in directionally solidified Sn–Ni peritectic alloys

Abstract

Sn–Ni peritectic alloys were directionally solidified using a Bridgman type directional solidification furnace. Microhardness (Hv) of both primary Ni3Sn2 phase and peritectic Ni3Sn4 phase and microstructure length scales including primary dendrite arm spacing λ1 were measured as a function of growth rate. Dependency of microhardness on the solidification processing parameters and primary dendrite arm spacing (λ1) in the directionally solidified Sn–36at.%Ni alloys were experimentally analyzed. The relationships between the solidification processing parameters (growth rate v and temperature gradient G) and microhardness, and primary dendrite arm spacing and microhardness were obtained by linear regression analysis: for primary Ni3Sn2 phase, Hv=501.06v0.07, Hv=5896.3λ1−0.42; for peritectic Ni3Sn4 phase, Hv=306.76v0.10, Hv=843.6λ1−0.69. It has been found that the values of λ1 decreases with the increasing values of v while the values of microhardness (Hv) increase with growth rate under constant G.