Strengthening of ultrafine PM aluminium using nano-sized oxycarbonitride dispersoids

Abstract

► Al compacts processed with powders milled under different amounts of NH 3 were prepared. ► NH 3 is decomposed during milling and N is incorporated into the Al powder. ► Nano-sized N rich dispersoids, formed during sintering, restrain Al grain growth. ► Compact properties follow a linear trend with respect to the amount of N incorporated. ► Controlling NH 3 allows producing ultrafine Al parts with pre-established properties. Composites consisting of ultrafine aluminium, mainly reinforced by in situ nano-sized oxycarbonitride dispersoids, were prepared by mechanical alloying followed by a simple press and sintering method. The mechanical alloying process was performed under atmospheres with different amounts of ammonia. Even when small amounts of ammonia were used, the gas was able to decompose at room temperature, with N incorporated into the aluminium powder. The sintered compact properties were strongly influenced by the amount of N incorporated into the powders during milling, with an almost linear trend for some of these properties.