Plastic deformation of a binary Cd–Yb icosahedral quasicrystal

Abstract

Polycrystalline icosahedral quasicrystals in a binary Cd–Yb alloy have been compressed at high temperatures for the first time. As-grown specimens were plastically deformable only above 698 K with the yield stress rapidly decreasing with increasing temperature. The true stress vs. true strain relation revealed continuous work softening to a large strain; the decrease of the true stress reaches 85% of the yield stress at 698 K and it is 20–50% at 773 K. Temperature change tests showed that the flow stress is sensitive to the deformation history; once a specimen has been initially deformed to a large strain at 773 K, it is plastically deformable even at 600 K. The activation analysis showed that the activation enthalpy decreases to two-third of that at the yielding stage as the strain increases, which is the cause of the work softening.