The phase diagram of the mercury-indium alloy system

Abstract

SUMMARYThe mer~u~-indium phase diagram has been investigated over the whole composition range from -7S"C to the melting point of indium, using thermal analysis, X-ray and superconductivity techniques. This is believed to be the first application of superconductivity measurements to phase diagram investigations. A compound, HgIn, of very limited range of composition, melts congruently at --1g.3'C;and gives rise to eutectics at 61.5 at.% indium and -31"C, and at 34.7% indium and -37.2%. The b phase extends from a.5 to 19.1% indium and has a maximum melting point of -rq.z"C at 14.2% indium. It forms a peritectic or eutectic at a temperature indistin~uishabie from the melting point of pure mercury with a solid solution in mercury containing some, but less than 0.3%, indium. A transition from face-centred tetragonal to face-centred cubic in the indium-rich solid solutions at about 93% indium gives rise to a peritectic at 108°C. The solubility of mercury in this face-centred cubic phase falls from about 22% at -3r"C to 73% at -78°C.

X-ray diffraction studies of the Hg–In alloy system

“…The residual resistivity curve reported by Coles, Merriam & Fisk (1963) is in good agreement with our conclusions. This curve shows a practically continuous increase of the resistivity with increasing indium concentration up to about 15 at.…”

“…This result is obviously not in agreement with others previously published Jangg, 1962;Kozin & Tananaeva, 1961) where a very small solubility of In in Hg was proposed. Coles et al (1963) also presented one X-ray Debye-Scherrer pattern for the 7.7 and 14.3 at.% In alloys saying that they were the reproducible results of a number of different experiments. This pattern is not the same as the one we obtained (pure Hg pattern).…”

“…(a) The discontinuity in the superconducting transition temperature refered to by Coles et al (1963) at about 2 at.% In is rather small, compared with other discontinuities observed at the concentration where there are true phase changes.…”

“…Hence, there are approximately 0.5 molecules of HgIn compound per unit cell, apparently indicating an entirely disordered phase. Coles et al (1963) also present a Debye-Scherrer pattern for the HgIn compound which was subjected to the same source of error as for the fl phase.…”

“…The phase diagram of the Hg-ln alloy system was obtained by Coles, Merriam & Fisk (1963) using differential thermal analysis and superconductivity data and, also, independently by G. Jangg (1962) and by Kozin & Tananaeva (1961). Their phase diagram shows evidence of a ,B phase in the range of concentration from 2 to 18 at.% In.…”