Tensile mechanical behavior of TiAl(FL) at high strain rate

Abstract

The tensile mechanical behavior of Ti-47at%Al-1.5at%Cr-0.5ar%Mn-2.8at%Nb in full lamellar microstructure has been studied in the strain rate range from 100 s−1 to 800 s−1 and the complete stress-strain curves were obtained. Results show that the alloy is extremely brittle at different strain rate, exhibiting near-zero ductility. Both UTS and fracture strain of material are strain rate sensitive, increasing with the strain rate at room temperature. Fractography analysis indicates that the alloy fractures in a mixed mode of predominant transgranular cleavage and minor intergranular cracking. On basis of the experiment results and Weibull distribution theory, a statistic model has been developed to describe mechanical behavior of TiAl(FL) at different strain rate. The statistical parameters for material and their relationships with strain rate are obtained from tensile impact experimental results. The simulated stress strain curves from the model are in good agreement with the test data. The theoretical model and test results show that both the scale parameter σ0 and the shape parameter β are rate dependent, and a linear dependence of σ0 and β on lg ɛ∈ has been found.