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 °C, was directionally solidified upward with a constant growth rate (V=3.2 μm/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 (λ) and micro-hardness (H v ) were measured from both the transverse and longitudinal sections of the samples. The dependence of the lamellar spacings (λ) and microhardness (H v ) on the temperature gradients (G) were determined by means of linear regression analysis. According to these results, the value of λ decreases as the value of G increases and the value of H v increases for a constant V. The results obtained in this work are compared with previous similar experimental results obtained for binary or ternary alloys.