Abstract
1. Ternary diagram of Aluminium-Silicon-Chromium alloys.
The diagram of Al-rich alloys containing silicon and chromium was investigated by means of thermal analysis, microscopic and X-ray examination. Al-rich corner up to 12% silicon and up to 4% chromium was studied. From several constitutional sections which have the same chromium-content respectively, the following conclusions were drawn: (1) In the range studied, the primary crystals are (Al), θ, η, α, β and Si. (2) The ternary refined compounds α and β are found to exist. (3) The non variant points are:
Liq.+Al11Cr7_??_Al7Cr+α, at 647°,
Liq.+Al7Cr_??_(Al)+α, at 630°,
Liq.+α_??_(Al)+β, at 626° and
Liq._??_(Al)+Si+β, at 576°.
2. Effect of chromium on mechanical properties of Al-Si alloys.
By adding of 0.3% chromium to the Al-Si alloys (5 to 12%Si), the micro-structure of sand casting and the mechanical properties are improved.
