Al-AlN tri-modal composites prepared by mechanical alloying

Al/AlN particulate composites were prepared by mechanical alloying (MA) of Al powder in NH(3) or N(2) atmosphere. The AlN phase formed only by a combination of MA in NH(3) and subsequent sintering. To improve the mechanical properties of the resulting Al/AlN bimodal composites, the mechanically alloyed Al powder was mixed with pristine Al powder and sintered. This resulted in (Al/AlN)/Al trimodal particulate composites with interesting properties. The outer part of the composites was hardened during sintering, showing the possibility of surface hardening by simple sintering in Al alloys.