High-temperature strength and deformation of ?/?? two-phase Co–Al–W-base alloys
The high-temperature strength and deformation behavior of ?/?? two-phase Co–Al–W-base alloys have been studied with polycrystalline and single-crystal materials. The ternary, quaternary and higher-order alloys containing Ta, Cr and/or Re exhibit flow stress anomalies above 873 K due to slip of pairs of 1/21 1 0 superpartial dislocations on {0 0 1} planes, in addition to {1 1 1} planes, in the ?? precipitates. Compression tests on the single-crystal specimens reveal a true anomalous peak temperature of 1073 K for both ternary and Ta-containing quaternary alloys. Above the peak, the ternary alloy exhibits a rapid decrease in strength with temperature, as 1/21 1 0 dislocations bypass the ?? precipitates without significant shearing. Conversely, the Ta-containing quaternary alloy sustains strength to higher temperatures due to the activation of 1/31 1 2 partial dislocation slip that introduces a high density of stacking faults in the ?? precipitates.
Akane SuzukiaEmail:suzukia@ge.com?Tresa M. Pollockb
[a]GE Global Research, One Research Circle, Niskayuna, NY 12309, USA;[b]Department of Materials Science; Engineering, University of Michigan, 2300 Hayward Street, Ann Arbor, MI 48109, USA
