Influence of Small Amounts of Boron on the Structural Evolution of Nanocrystalline Ni₃Al During Thermal Treatments

Abstract
The influence of a boron addition (0.1 wt%) on the structural stability of high-purity nanocrystalline Ni₃Al intermetallic compounds was investigated. The nanocrystalline structure was obtained by severe shear deformation under quasi-hydrostatic pressure. Residual electrical resistivity, Vickers microhardness, X-Ray diffraction and transmission electron microscopy were used to characterize the material evolution during thermal treatments in the temperature range 293-1313 K. After severe deformation the materials were disordered with a smaller crystallite size in the boron-doped compound than in the pure one. The boron addition was found to shift the long-range ordering, as well as the recovery of the properties investigated to higher temperatures, i.e. to improve the thermal stability of the structure.