STRUCTURAL PHASE TRANSFORMATIONS IN THE INDIUM-RICH SOLID SOLUTIONS

It is shown that there are four kinds of phase transformation in Indium-rich alloys containing solute atoms such as Cd, Hg, Tl, Sn and Pb as follows : (1) fcc [MATH] fct(c/a>1), (2) fcc [MATH] fct(c/a1) and (4) fct(c/a1). The results obtained in these transformations are discussed m terms of the Landau theory based on the group theory. It is concluded that a responsible representation for these transformations is two-dimensional representation Eg belonging to the cubic point group Oh. The fcc [MATH] fct transformation in In-Tl, In-Cd, In-Hg and In-Pb alloys and the fact(c/a<1) [MATH] fco in In-Pb-Sn alloys are quantitatively analyzed in terms of the Gibbs free energy, which is expressed by two order parameters such as two spontaneous strains corresponding to the two-dimensional representation Eg. The effect of the electron-atom ratio and the atomic size on the transformation behaviour is also discussed