The effect of growth rate on microstructure and microindentation hardness in the In-Bi-Sn ternary alloy at low melting point

In-21.5 at.% Bi-17.8 at.% Sn ternary alloy which has 333 K melting point was directionally solidified upward with a constant temperature gradient (G = 0.91 K/mm) in a wide range of growth rates (3.2-157.1 mu m/s) with a Bridgman type directional solidification furnace. The lamellar spacings (lambda) and microhardness values (H-V) were measured from both transverse and longitudinal sections of the samples. The dependence of lamellar spacings (lambda) and microhardness (H-V) on the growth rate (V) was determined by using linear regression analysis. According to these results, it has been found that the value of lambda decreases with the increasing value of V and whereas, the value of H-V increases for a constant G. The values of lambda V-2 were determined by using the measured values of lambda and V. The results obtained in this work have been compared with the previous similar experimental results obtained for binary or ternary alloys. (C) 2008 Elsevier B.V. All rights reserved.