Deformation behavior of the CuAu alloy ordered under external compressive or tensile load

To manage the structure evolution and properties formation, the external compressive and tensile loads (up to 20 MPa) were applied to CuAu alloy specimens during their ordering by cooling from 500°С at the rate of 12 deg/h. To find changes in the texture, XRD-scans and dilatometry investigations were used. Stress-strain curves obtained by tensile tests of ordered specimens were analysed. Both yield strength and strengthening rate of the specimens ordered under compressive load slightly increase. Moreover, the specimens show impressive thermal expansion at order→disorder phase transition that may be of interest for practical applications. Yield strength of the specimens ordered under tensile load decreases; however, their ultimate tensile strength and elongation to failure significantly grow. The discovered effects are explained by differences in flow mechanisms due to a change in the orientation of the domain boundaries in the specimens ordered under different load conditions. The strengthening rate of the ordered CuAu alloy is shown to be a non-monotonic dependence with its maximum near the true strain ε ≈ 0.25. A complex shape of the strengthening rate vs. true strain curves is explained by a change in the predominant deformation mode.