Effect of secondary processing on the microstructure and wear behavior of spray formed Al–30Mg 2 Si–2Cu alloy

Abstract

In the present work, Al–30Mg 2 Si–2Cu alloy has been spray formed and subsequently hot pressed for den- sification. The alloy is then subjected to solutionizing and isothermal aging treatments. The microstruc- tural features, hardness and wear behavior of spray formed and secondary processed alloys have been evaluated individually and compared with that of as-cast alloy. The microstructure of spray formed alloy showed refined and globular shaped primary Mg 2 Si intermetallic particles and Al 2 Cu precipitate particles uniformly distributed in Al matrix. The microstructure was refined further after hot consolidation. The microstructure after solution heat treatment appeared similar to that of the spray formed alloy but aging led to a further refinement in the microstructure compared to that of the hot pressed alloy. The evalua- tion of wear behavior of these alloys, under dry sliding condition, showed that the age hardened alloy exhibits maximum wear resistance and minimum coefficient of friction over the entire range of applied load (10–50 N) at a sliding speed of 2 ms 1 followed by hot pressed, spray formed and solution heat trea- ted alloys. The as-cast alloy showed the least wear resistance and highest coefficient of friction. Similar trend has been observed even in their hardness values too. The wear resistance of the alloys is discussed in light of their microstructural modifications induced during spray forming and subsequent secondary processing and also the topography of worn surfaces.