Microstructure evolution and properties of powder metallurgy Ti43Al9V0.3Y alloy sheets at different rolling temperatures

TiAl alloy is a new type of lightweight high temperature structural material with excellent properties. Its room temperature brittleness can be improved by refining the microstructure and adjusting the composition. In this study, the pre-alloyed powder was sintered and densified by hot isostatic pressing, and TiAl alloy sheets were prepared using hot pack rolling. The present work establishes a fundamental understanding of the microstructure and properties during hot rolling. An ultrahigh ductility TiAl alloy was prepared by a combination of introduction of twins, purifying matrix and high sphericity grains. The room temperature elongation of the TiAl sheet is 3.0% and the elongation reaches 65% at 700 degrees C. The high uniform malleability might be due to several reasons: (i) Some twins are formed during the rolling deformation, in the process of dislocation slip, twins can adjust the crystal orientation to facilitate the continued dislocation slip. In this way, twinning slightly improves the room temperature plasticity of TiAl alloys; (ii) Y purifies matrix of the TiAl alloy; (iii) the grain has the high sphericity, and the spherical grain could minimize the stress concentration.

Automated summary

The room temperature brittleness of TiAl alloy can be improved by refining the microstructure and adjusting the composition. TiAl alloy sheets were prepared through hot isostatic pressing and hot pack rolling, and the microstructure and properties during hot rolling were studied. An ultrahigh ductility TiAl alloy was successfully prepared by introducing twins, purifying matrix with Y element, and achieving high sphericity grains. The TiAl sheet exhibits a room temperature elongation of 3.0% and an elongation of 65% at 700 degrees C, which can be attributed to the formation of twins, purifying effect of Y element, and stress concentration reduction by spherical grains.