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

摘要

Sn-Ni peritectic alloys were directionally solidified using a Bridgman type directional solidification furnace. Microhardness (Hv) of both primary Ni_3Sn_2 phase and peritectic Ni_3Sn_4 phase and microstruc-ture length scales including primary dendrite arm spacing λ_1 were measured as a function of growth rate. Dependency of microhardness on the solidification processing parameters and primary dendrite arm spacing (λ_1 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 Ni_3Sn_2 phase, Hv = 501.06v~(0.07), Hv = 58963λ_1~(-0.42) for peritectic Ni_3Sn_4 phase, Hv = 306.76v~(0.10), Hv - 843.6λ_1~(-0.69). It has been found that the values of λ_1 decreases with the increasing values of v while the values of microhardness (Hv) increase with growth rate under constant G.