EFFECTS OF CU AND SOLUTION HEAT TREATMENT ON THE MICROSTRUCTURE AND HARDNESS OF IN-SITU ALUMINIUM MATRIX COMPOSITE CONTAINING AL4SR PHASE

This study was undertaken to investigate the effects of cu and solution heat treatment on the microstructureand hardness of cast al-al4sr metal matrix composite. different amounts of cu (0.3, 0.5, 1, 3 and 5 wt.%) were addedto the composite. specimens were heat treated at 500 °c for 4 hours followed by water quenching. microstructuralstudies were assessed by the use of optical microscope, scanning electron microscope (sem) and x-ray diffractometry(xrd). the results showed that addition of 5 wt.% cu reduces the length of large needle-like al4sr phase and refinesthe microstructure. in addition, the presence of cu-intermetallics increases hardness of the composite. cu mainlyforms ? phase which segregates at the grain boundaries. heat treatment partially dissolves cu-intermetallics andhomogenizes the distribution of ? phase in the matrix.