Precipitate Refinement and Mechanical Property of Al-Fe Alloy Prepared by Compressive Torsion Processing

Abstract

The compressive torsion process (CTP) was applied to the preparation of Al-4wt%Fe casting alloy in order to refining large precipitates of Al-Fe intermetallic compounds and improving their mechanical properties. To examine the effects of CTP conditions on precipitate refinement and tensile property, CTP was carried out under different processing temperatures (373-573K) and different numbers of torsional revolutions (1-30 times). Large primary Al₃Fe precipitates hundreds of micrometers in diameter are broken and refined to 20µm or below by the severe plastic flow in CTP. Such precipitate refinement and uniform dispersion were promoted with increasing number of torsional revolutions and with decreasing process temperature. The tensile property of the alloy processed by CTP was remarkably improved compared with that of the cast alloy before CTP. It was 1.7 times in tensile strength and about 8 times in total elongation. Thus, it was concluded that CTP is very effective in refining large precipitates and improving the ductility of Al-Fe alloy.