Correlation of the Mechanical Properties of Polycrystalline Ni3Al Alloys with Their Electronic Structure

The electronic structure of Ni;Al alloys with different B contents has been investigated by measuringthe positron lifetime spectra.The segregation of B atoms to defects could form strong covalentbondings with Ni and Al atoms and make the electronic structure in those locations similar to that inbulk,thus strengthen their cohesion.The interaction of B atoms,which were solid-solutioned in thecrystal lattice of Ni;Al in a manner of occupying interstitial sites,with Ni and Al atoms resulted in theincrease of the density of valent electrons,thus increased the bonding cohesion in bulk.The im-provement of the mechanical properties of Ni;Al alloys by B doping was due to both“grain bounda-ry effect”and“bulk effect”of B,which correlated with their electronic structure.