THE TERNARY-SYSTEM ALUMINUM-GOLD-SILICON

We calculated the two pseudobinary systems Al2Au-Si and AlAu2Si and the Si liquidus surface at 1373 K. The Al-Au and Al-Si binary systems reported by Massalski and Hultgren agree with each other, but differences are present in the Au-Si system. fn the Al-Si system the Si liquidus extends over a temperature range of 800 K, and in the Au-Si system over 1000 K. This permits us to check the new equation for the difference in Gibbs energy G(1-s) and specific heat C-p(1-s) derived from the consideration of T-glass the theoretical glass transition temperature. For the liquid solutions we used the Hoch-Arpshofen model. The only available ternary experimental data are the Si liquidus compositions at 1373 K obtained by Lozovdkiy and Politova. The agreement between experimental and calculated data is very good. The calculated eutectic compositions and temperatures are as follows: for the 1/3Al(2)Au-Si system a eutectic temperature of 1.195 and an Si content x=0.175; for the 1/3AlAu(2)-Si system a eutectic temperature of 0.760 and an Si content x=0.113.