Fabrication of an r-Al₂Ti intermetallic matrix composite reinforced with α-Al₂O₃ ceramic by discontinuous mechanical milling for thermite reaction

In this study, a powder mixture with an Al/TiO₂ molar ratio of 10/3 was used to form an r-Al₂Ti intermetallic matrix composite (IMC) reinforced with α-Al₂O₃ ceramic by a novel milling technique, called discontinuous mechanical milling (DMM) instead of milling and ignition of the produced thermite. The results of energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) of samples with varying milling time indicate that this fabrication process requires considerable mechanical energy. It is shown that Al₂Ti-Al₂O₃ IMC with small grain size was produced by DMM after 15 h of ball milling. Peaks for γ-TiAl as well as Al₂Ti and Al₂O₃ are observed in XRD patterns after DMM followed by heat treatment. The microhardness of the DMM-treated composite produced after heat treatment was higher than Hv 700.