-Component plastic displacements in different microstructures of TiAl-base intermetallics

摘要

Three different microstructures of a near-gamma Ti-48Al-2Cr-2Nb-B (at.%) alloy, nearly lamellar (NL), equiaxed with a low alpha_2 phase volume fraction (ELA), and equiaxed with the high alpha_2 phase volume fraction (EHA) were investigated. The three microstructural types exhibited different creep behaviour at 973 K and 350 MPa. Interrupted creep tests were performed to assess the evolution of dislocation densities and deformation twinning with increasing creep strain. Results of the quantitative analysis suggest that deformation twinning represents a relevant contribution to the strain accumulation kinetics at high temperatures and makes NL and EHA microstructures less creep resistant but more ductile.