Enhanced mechanical properties of an Al based metal matrix composite prepared using mechanical alloying

An Al-4.5wt.%Cu-10vol.%SiCp composite has been prepared using a mechanical alloying technique. The structural evolution of the mechanically alloyed powder mixture was monitored using X-ray diffractometry while its thermal behaviour was determined using differential scanning calorimetry. The results showed that both the 0.2% yield and the ultimate tensile stresses increased with the duration of mechanical alloying. This increase is associated with the homogeneous distribution and refinement of the SiC particulates, the formation of oxides and the decreased grain size. The thermal fatigue behaviour of the composite has also been investigated using thermal cycling between - 15 and 150 degrees C. The tensile tests on the thermal cycled specimens were carried out to study the influence of thermal cycling on the mechanical properties of the material. It was found that although the 0.2% yield and the ultimate tensile stresses had improved, cracks had been observed in the matrix material. These cracks may have led to the final failure of the test specimens. (C) 1998 Elsevier Science S.A. All rights reserved.