Low Temperature Mechanical Behavior of Ni-15Cr-Al-Ti-Mo Alloys.

摘要

A series of Ni-15 Cr-Al-Ti-Mo alloys with varying gamma-gamma' mismatch, Ti/Al atomic ratio, and weight fraction of gamma' were tension tested at ambient temperature after aging to peak yield strength at 760 C. After subtracting the alloy yield stress in the solution treated condition, oss, the increment in yield stress due to precipitation of gamma', (Delta sigma Y), was found to be principally influenced by the weight fraction of gamma' and the measured gamma-gamma' mismatch. Only a small contribution of APBE to alloy strength was observed between two compositions of similar mismatch and differing measured APBE. The work hardening behavior of the alloys was similarly influenced by weight fraction of gamma' and gamma-gamma' mismatch. Alloys with low mismatch exhibited sheared gamma' precipitates following tensile deformation. A model for shear of ordered gamma' precipitates by residual dislocation loops in low gamma-gamma' mismatch alloys is proposed to account for the low work hardening rates observed. (Author)