Rapid Sinterability of Mechanically Alloyed MgAl/MgO Composite with the Field-Assisted Sintering Technique

In this study, a Mg22Al/10MgO composite could be produced at nearly full density by the field-assisted sintering technique at relatively low temperatures and for short time such as 400°C and 15 min under the vacuum-argon atmosphere. The Mg22Al matrix consists of 22 wt % Al, produced by mechanical alloying for 18h and then mixed 2 h with 10 wt % MgO as a reinforcement material. The microstructure of the sample was analysed using an optical microscope, SEM, EDS and XRD. Mechanical properties such as micro hardness, density and compression strength are also obtained. With a compression strength of 314.4 MPa and a hardness value of 137 HV, the composite obtained nearly theoretical density-TD of 0.99. The crystal distortion was measured and calculated by using XRD results. Furthermore, minor amounts of fine intermetallic compounds and oxides such as Al₃Mg₂, AlMg, γ-Al₁₂Mg₁₇ Al₂O₃ and MgO were detected. The field-assisted sintering technique, which allows rapid and low-temperature sintering, is used in this study to show that the mechanical properties of the mechanically alloyed microstructure are likely to be preserved during sintering. Furthermore, it demonstrates that when Al and Mg are mechanically alloyed, the alloying pair is a very suitable metal matrix material for composites in which a reinforcing phase, such as MgO, forms an insufficient interface.