Microstructure evolution and mechanical properties for oxygen-rich ZrTiAlV alloy during in-situ semi-solid processing

Abstract

Oxygen-rich ZrTiAlV alloy reinforced by spherulite ZrO phase was prepared by in-situ semi-solid processing. The results of high temperature (500°C) mechanical properties test confirmed that alloy elongation after semi-solid processing at 1500°C was close to that for the as-forged material, whereas yield and tensile strength were increased by 66.4% and 30.8%, respectively. SEM and EBSD results confirm that morphology selection of non-equilibrium growth is mainly controlled by the initial core shape, with dendrites always growing along the <110> direction following the Twin-Plane-Reentrant-Edge mechanism. Improved alloy strength is attributed to fine grain strengthening and precipitation strengthening caused by the ZrO phase, and α phase spheroidization ensures alloy plasticity. We also propose a crack deflection toughening mechanism for the alloy.