Investigation of microstructural, hardness, and thermal properties of mechanically milled Al-Co-Cu-Mg alloys

Abstract

In this study characterization of a novel Al66Co20Cu13Mg1 alloy produced by the mechanical alloying method was investigated. The effect of milling time on the produced alloy's microstructural evaluations, microhardness, and thermal behaviors was investigated. Scanning electron microscope and X-ray diffractometer results demonstrated that as the milling time was increased, the homogeneity was increased, the particle size was decreased, crystalline cubic Al(Co, Cu) solid solution, α-Co(Cu, Mg) solid solution phase and Al2Cu phase were formed with the mechanical alloying effect after milling of 50 h. When the powder alloy was milled for 100 h, most of the elemental peaks such as Al and Cu disappeared, and Al3.892Cu6.108 phase was formed. The crystallite size of the alloy powders after 100 h of milling was found as 17.42 ± 2 nm. Moreover, as the milling time was increased, both the lattice strain and dislocation density were increased because of fractures, the formation of new intermetallic phases, and excessive deformations. The microhardness of the pressed powder alloys was increased due to the cold welding and intermetallic phases formed in the powder alloy with increasing milling times. The lowest and highest microhardness values are found to be 275 ± 10 and 376 ± 10 HV for the unmilled alloy and the 100 h of milled alloy, respectively.