Dependency of Microstructural Parameters and Microindentation Hardness on the Temperature Gradient in the In-Bi-Sn Ternary Alloy with a Low Melting Point

The ternary alloy In-21.5 at.% Bi-17.8 at.% Sn, which has a melting point of 60 degrees C, was directionally solidified upward with a constant growth rate (V = 3.2 mu m/s) and different temperature gradients (G = 0.91 K/mm to 2.85 K/mm) by using a Bridgman-type directional solidification furnace. The lamellar spacings (lambda) and microhardness (H(v)) were measured from both the transverse and longitudinal sections of the samples. The dependence of the lamellar spacings (lambda) and microhardness (H(v)) on the temperature gradients (G) were determined by means of linear regression analysis. According to these results, the value of lambda decreases as the value of G increases and the value of Hv increases for a constant V. The results obtained in this work are compared with previous similar experimental results obtained for binary or ternary alloys.