High-temperature creep behavior and hot-pressing consolidation of NiAl

Abstract

Abstract The steady-state creep behavior of NiAl was studied by constant strain-rate tests in the strain-rate regime 1.5 × 10−4≤ ɛ̇ ≤ 1.0 × 10−2 s−1.Primary creep of NiAl was investigated at different stresses (10 MPa−40 MPa) in the temperature range from 1200 to 1400°C. The steady-state creep rate was fitted to a temperature-compensated power-law expression ɛ̇ = B(σ/μ) n exp(−Q/RT), from which a stress exponent n≈3.5 and an activation energy Q ≈ 398 kJ/mol were derived, respectively. The obtained activation parameters indicate that dislocation creep dominates the creep behavior of NiAl at temperatures above 1200°C up to 1400°C. The transient creep behavior at 40 MPa could be fitted to a power-law equation ε = ε 0 + btm with b α σ3:5 and 0.52<m<0.68. The creep data of NiAl obtained in this study were utilized for modeling and simulation of the consolidation process of NiAl composites during hot pressing by finite-element analysis.