DEVELOPMENT OF POWDER COMPOSITE BASED ON AL–SI–NI SYSTEM AND TECHNOLOGY FOR MAKING BILLETS OF THIS COMPOSITE

Abstract

The paper provides the results of alloy development investigation and technology of making compact billets of the Al-Si-Ni-based composite for aerospace equipment components. Composite production included several stages: first, matrix powder was produced by gas atomization and then matrix powder with disperse alloying additives was mechanically alloyed in high-energy machines. The vacuum press, unique equipment located at OJSC «Kompozit» (Korolyov, Moscow region, Russia), was used to develop and test the technology of mechanically alloyed composite degassing in a thin layer (to eliminate material ejection from the container when degassing a large volume of powder) as well as to tryout composite compaction process modes. Cylindrical billets up to 100 mm in diameter and up to 120 mm in height were obtained based on this technology. Kompal-301, a newly developed and patented composite, has significant advantages compared to the SAS-1-50 sintered aluminum alloy due to 1,5 times lower thermal coefficient of linear expansion and 2–3 times higher precision elastic limit with the same density values. The compacted billet has a resulting matrix structure with disperse silicon excess particles distributed quite uniformly over the aluminum solid solution. There are some larger isolated silicon particles in certain structure areas. Unfortunately, they cause lower billet ductility so it is impossible to produce semi-finished products by plastic deformation. However, such a low ductility has no negative effect on the billet production itself.