Solute hardening and softening effects in B2 nickel aluminides [report]

L.M. Pike, C.T. Liu, I.M. Anderson, Y.A. Chang
1998 unpublished
The effect of substitutional solute additions including Fe, Mn, and Pd on the hardness of B2-ordered NiAl alloys was investigated. The solid solution hardening behavior of intermetallics is more complex than that of typical metallic solid solutions because of complications arising from the site preference of the solute as well as the effects of the solute on the concentrations of other point defects, e.g. vacancies and anti-site defects. For this reason, care was taken to experimentally
more » ... erimentally establish solute site preferences and point defect concentrations in the NiAl alloys before analyzing the hardness data. By taking these factors into account it was possible to rationalize the observed unusual hardening effects. Three distinct categories of solid solution hardening behavior were encountered. The first was hardening by the solute addition itself. This was observed in the case of Pd additions to AI-poor NiAl. However, when Fe or Mn is added to AI-poor NiAl a second category is observed; these elements are seen to soften the material. The third category of behavior is observed when Fe is added to NiAl with a constant AI concentration of 50 at. %. In this case it is vacancies, rather than solute atoms, which harden the material.
doi:10.2172/676873 fatcat:vnzfipcohbcm3fqagfkx2wampy