Effect of mechanical alloying on structure and property of Ni₃Al by spark plasma sintering

Abstract

Ni₃Al intermetallics have been successfully made from mechanically alloyed powder with nominal compositions Ni₇₅Al₂₅ (at.%) by spark plasma sintering (SPS). The effect of mechanical alloying on the microstructure of elemental powder and the properties of as-sintered alloy has been investigated by X-ray diffraction (XRD), scan electronic microscopy (SEM), density measurement and bending test. The results show that the mechanical alloying (MA) refines the grain of particles. It suggests that during subsequent sintering processes the high energy powder enhanced by MA needs lower sintering temperature than mixture powder to gain single phase Ni₃Al compacts. Under the same sintering conditions, density and strength of Ni₃Al compacts increase with milling time initially and then began to decrease with prolong of milling time under the interaction of grain refinement and more defects involved by MA. Sintering temperature has significant influence on the purity of Ni₃Al in the compacts fabricated by reaction synthesis.

Keywords:

• NI3AL INTERMETALLICS
• MECHANICAL ALLOYING
• SPARK PLASMA SINTERING