Microstructure, mechanical properties, hot deformation and oxidation behavior of Ti-45Al-5.4V-3.6Nb-0.3Y alloy

gamma-TiAl alloys are regarded as promising structural materials for extensively using in the fields of aerospace, automobile vehicle and chemistry. In this paper, microstructure, properties and hot deformation behavior of Ti-45Al-5.4V-3.6Nb-0.3Y alloy were investigated. SEM, XRD and TEM results showed that the alloy mainly composed of gamma. alpha(2) and beta phase had fine nearly lamellar microstructure with colony size of 50-70 mu m, beta and gamma phase located at the colony boundaries. In addition, some beta precipitations appeared at gamma/gamma interfaces. Tensile test results exhibited that the yield strength (YS) and ultimate tensile strength (UTS) of the alloy were decreased from 400 MPa and 460 MPa at room temperature to 350 MPa and 420 MPa at 700 degrees C, respectively, and the elongation (delta) of the alloy was increased from 0.55% at room temperature to 2.63% at 700 degrees C. The fracture surfaces exhibited primary translamellar character at all test temperatures. Ti-45Al-5.4V-3.6Nb-0.3Y alloy showed excellent deformability at elevated temperature since some (3 phases exist at the colony boundaries. At 800 degrees C, the alloy owned a good oxidation resistance due to the presence of an almost fully dense oxidation layer with an alternating structure which formed during oxidation processing. (C) 2010 Elsevier B.V. All rights reserved.