Thermal analysis of In-Pb system

Abstract

While the overall form of the In-Pb system is reasonably well established, there is uncertainty about the equilibrium position of the solidus. Hansen and Anderko in their review of previous investigations of this system pointed out that much of the data that had been obtained from cooling curves was likely to be unreliable in that the width of peritectic horizontals would be greater than the equilibrium values, and that solidus temperatures would tend to be lower than the equilibrium values. Both effects are due to the large change in composition of the solid phase, up to 0.5 at.-% °C⁻¹, which must occur as alloys are cooled if equilibrium is to be maintained. Such changes do not occur in these alloys at the cooling rates of a few degrees per minute commonly employed, and the alloys therefore develop a cored structure. The position of the liquidus is, of course, not affected in this way, and cooling curves can provide reliable liquidus values.