Directionally Solidified Microstructures And Peritectic Phase Growth Of Cu-75%Sn Peritectic Alloy

Directionally solidified microstructures of Cu-75%Sn peritectic alloy were investigated at the growth rate ranging from 1 to 300 mu m/s. With the growth rate increasing, directionally solidified plate-like microstructures in Cu-75%Sn peritectic alloy are refined by the increase of nucleation quantities of primary E phases and cooling rate. Peritectic eta phase can grow by the peritectic transformation and direct solidification from the liquid. At the low growth rate varying from 5 to 10 mu m/s, the width of e phase increases due to the effect of the peritectic transformation; however, at higher growth rate, the deviation between the width of E phase and the whole plate-like microstructure increases resulting from direct solidification of eta phase from the undercooled melt. The regressed data show that the relationship between the width of the whole plate-like microstructure (W) and the growth rate (v) satisfies as W nu(0.27) =117 mu m(1.27) (center dot) s(-0.27) and the primary dendritic arm spacing (lambda) with the growth rate has a relation of lambda nu(0.208) = 153.8 mu m(1.208 center dot) s(-0.208) as the growth rate increases from 3 to 300 mu m/s.