Experimental investigation of the Cu–Si phase diagram at x(Cu)>0.72

Abstract

Cu–Si phase equilibria have been investigated at compositions greater than 72 at.% Cu by X-ray diffraction, optical and electronic microscopy, electron probe microanalysis and differential thermal analysis.The general aspects of the phase equilibria already reported in literature have been substantially confirmed, but selected composition ranges and the nature of a few invariant equilibria have been modified. In particular stability ranges of the β, δ and η phases have been slightly modified as well as temperature and nature of the invariant equilibria related to the γ ⇄ δ transformation.Stability of the ɛ-(Cu15Si4) phase has been especially investigated concluding that it is thermodynamically stable but kinetically inhibited by nucleation difficulties which become especially effective when samples are synthesized in very high purity conditions.Crystal structure and composition ranges of the high temperature β and δ phases, despite difficulties by the non-quenchability of these phases, have been investigated by different methods including high temperature XRD.

On the binary (Cu+Si) system: Thermodynamic modelling of the phase diagram and atomic mobility in face centred cubic phase

“…The invariant reactions in the solid and solid/liquid states were measured by Smith [25,26], by Iokibe [29], and by Sufryd et al [27]. Generally, all the data agree well with one another.…”

“…After that, a number of papers about the liquidus curves for Cu rich side were published by Smith [24][25][26] and by Sufryd et al [27]. The solidus line for the FCC_A1(Cu) phase was determined by Rudolfi [23] The phase boundaries in a solid state were determined by Smith [24] and Andersen [28] who described a boundary of FCC_A1(Cu) phase and by Sufryd et al [27] who determined boundary of b, d and j phases based on DTA experiment.…”

On the influence of the stacking sequence in the nucleation of Cu3Si: Experiment and the testing of nucleation models

“…Cu 3 Si is the only congruently melting phase of the copper-silicides and also lies the closest to the deepest eutectic point. Furthermore it is characterized by the highest formation enthalpy (13.6 kJ mol À1 [8] as compared to 10.5 kJ mol À1 for Cu 5 Si [8]; to the best of our knowledge no calorimetric data is available for Cu 15 Si 4 but its formation seems to be kinetically inhibited [25]). Therefore this phase is expected to nucleate at the interfaces.…”

Role of different factors affecting interdiffusion in Cu(Ga) and Cu(Si) solid solutions

“…Rhines & Mehl [13] calculatedD by a slicing spectroanalysis method only at 1000 • C where the solubility of Si in Cu is around 5 at.% Si [14]. Minamino et al [12] investigated interdiffusion on Cu-Si over wide temperature 725-900 • C and composition ranges (up to 9.8 at.% Si).…”