Abstract
An Al–12Si alloy has been laser alloyed using premixed powders and a carbon dioxide laser. Tracks 6 mm wide were alloyed with various amounts of Si, Ni, Fe, Cu, Mn, Cr, Co, Mo, and Ti and assessed for integrity,uniformity, hardness, and response to age hardening. In general, above a certain concentration the tracks were smooth with high integrity. Alloys containing more than 30%Fe cracked, and Mo and Ti were difficult to melt. Aging at 150aC for 25 h produced a significant increase in the hardness of Cu, Mn, and Cr alloyed tracks. Coatings 18 mm wide were alloyed with a series of Al–Ni and Al–Fe compositions containing various amounts of Cu, Mn, and Cr. After aging, the coatings were characterised and their resistance to cavitation erosion and sliding wear was determined. Additions of Cu, Mn, and Cr considerably increased the hardness of the Ni based coatings. In general, thecoatings had excellent properties. The resistance to erosion was very high, the best coating having an erosion rate 0.03 times that of the Al–12Si base material. Many coatings had a wear rate down to 0.2 times that of Al–12Si, but in some cases the wear rate was increased.
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