Effect of processing parameters on characteristics of an Al-Al۲Cu composite produced in situ by powder metallurgy

Al-Al۲Cu composites due to their high Youngʼs modulus, good compressive strength, ductility, good tensile properties and high hardness have gained a lot of attention. There are different methods for fabrication of these composites. In the present investigation, an Al-Al۲Cu composite fabricated in situ by powder metallurgy. Commercially pure Al powders (۳۸-۷۵ μm) and commercially pure Cu powders (<۴۵ μm) were initially chemically treated with ۱% NaOH and ۱۵% HCl respectively to ensure their surface activation before blending. Then the Al/Cu powder mixtures containing ۲۰ wt.% of Cu powders were cold pressed in a steel die at ۷۵۰ MPa using a ۴۵ ton hydraulic press. The resultant cylindrically shaped samples were subjected to sintering at different temperatures for different times. The results of XRD and SEM studies as well as microhardneess and hardness measurements revealed that the optimum sintering time and temperature were ۶۰ min and ۶۰۰˚C respectively. Also a sample was fabricated at identical condition using the same Al powder with no Cu addition to serve as the reference sample. SEM studies revealed that sintering the Al-Al۲Cu eutectic generated by reaction between Al and Cu distributed uniformly in the Al matrix. All the composites exhibited higher hardness values as compared with their reference counterparts.

Keywords:

In situ Al-Al۲Cu composites , Powder metallurgy , Microstructure , Microhardness , Hardness.