Effects of milling time on sintering properties and formation of interface Al4C3 on graphite reinforced Al-4.5Cu-1.5Mg nanocomposite

Abstract

Aluminum-based metal matrix nanocomposites have been extensively researched and developed for aerospace and automotive applications. Al-4.5Cu-1.5Mg with 0.5 wt% graphite were milled for 2 h, 4 h, 6 h, and 8 h using shaker mill under argon gas. The phenomena of deformation, fracturing, and cold welding during shaker mill were investigated to observe how the shaker mill effects on their morphology and formation of intermetallic phases due to its very high speed. Sintering under ultra-high purity argon gas for 99.9999% was done to produce high density materials. Intermetallic phase Al4C3 was found as a result reaction between aluminum and graphite during milling. Formation of Al4C3 is very important to the alloy as an interface between matrix and reinforcement particle in order to have higher hardness.  A decrease in Peaks Cu and followed by an increase in Al2Cu precipitation in the XRD pattern occurred with increasing milling time. The role of Al2Cu precipitation is very important in improving mechanical properties, resulting in the highest hardness value reaching 97 HV and a density value of 83% at 8 h of milling.