Synthesis of nanocrystalline NiAl over a wide composition range by mechanical alloying

Abstract

The paper reports the synthesis of nanocrystalline NiAl by mechanical alloying of pure metal mixture and a mixture of prealloyed powder with Ni/Al. A large number of compositions have been studied to establish the phase field of NiAl in the milled state. The phase field of NiAl in the ball milled condition was found to be much wider (10-68 at.% Ni) than its equilibrium phase field (45-59at.% Ni). The metastable equilibrium achieved by mechanical alloying was identical for a given composition irrespective of the starting ingredients. The crystallite size of NiAl reached a minimum (5 nm) at the phase boundary of NiAl/Ni3 Al.