Study on the phase diagram of Al-Si-Sr ternary alloy system

Abstract

The aluminum corner of Al-Si-Sr ternary alloy system was investigated by means of inverse rate thermal analysis, identification by X-ray diffraction, EPMA analysis and microscopic observation. A ternary compound SrAl2Si2, named “T”, exists in this ternary system and Al-T line is considered as a quasibinary system with a eutectic point at 1.1%Si, 2.4%Sr, 645°C. The aluminium corner is divided into two regions by the Al-T quasibinary system. A ternary eutectic point was determined to locate at 575°C, 13.1%Si, 0.03% Sr, which is very close to the Al-Si binary eutectic point. The modification effect of small amount of strontium addition on Al-Si alloys can be regarded to be due to the formation of fine ternary eutectic structure. In the Al-SrAl4-T region, a ternary eutectic point was found to locate at 643°C with 1.7%Si, 2.4%Sr. © 1985, The Japan Institute of Light Metals. All rights reserved.