MICROSTRUCTURAL EVALUATION OF ZrC REINFORCED Al-Cu MATRIX ALLOY COMPOSITES FABRICATED BY MECHANICAL ALLOYING AND VACUUM HOT PRESSING

摘要

In this work, Al-4wt.%Cu composites comprising two differently sized ZrC reinforcing particles (157μm and 8μm) were fabricated by high energy ball milling and vacuum hot pressing. Vacuum hot pressing experiments were carried out at 550°C under a pressure of 70 MPa on Al-4wt.%Cu composite powders ball milled for 3h. Effects of reinforcement size on the microstructural and physical properties of the composites were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy-dispersive spectrometry (EDS) techniques. Following vacuum hot pressing, approximately relative density values of 98% were achieved for all hot pressed Al-4wt.%Cu composites. Highest microhardness values were measured for the hot pressed Al-4wt.%Cu composites containing the smallest sized ZrC reinforcing particles (8 μm). On the basis of analysis, in addition to the Al, ZrC and Al_2Cu phase reflections, a tetragonal Al_7Cu_2Fe phase was formed due to iron contamination from balls and/or vial in the metal matrix composite during MA process.