Phase Formation During Mechanical Alloying and Subsequent Heat Treatment of Ni50-Ti25-Al25 Powders

Ni-Ti-Al intermetallics have many applications in industries due to their high physical and mechanical properties including high strength, thermal resistance and high corrosion resistance. Being simple and cheap, mechanical alloying followed by appropriate heat treatment is widely used to produce nanostructure intermetallic compounds nowadays. This study aimed at investigating the effect of ball mill time and the heat treatment after it on the formation of nanostructure intermetallic compounds in Ni50-Ti25-Al25 system. To do so, the Ni50Ti25Al25 mixed powder was prepared and milled in a planetary ball mill at different times. Products were evaluated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Upon milling for 100 hour, Ni3Al nanostructure intermetallic compound was formed. The mixed powder was obtained after 100 hours milling was annealed. Results obtained after heat treatment suggest the formation of ternary system of intermetallic compounds such as Ni3(Ti,Al) and Ni2TiAl as well as binary compounds. Given the formation of Ni-Ti-Al nanostructure system with desirable properties and considering the simplicity and low cost of the process, mechanical alloying and heat treatment can also be used to produce other intermetallic compounds.

Keywords:

Mechanical alloying , Nanostructure intermetallic compound , Annealing , Ni-Ti-Al system