Ti45Al10Nb合金全片层组织韧脆转变机制的研究

Effect of Strain Rate on Brittle-Ductile Transition Mechanism of the Ti45Al10Nb Alloy with Fully Lamellar Microstructure

研究了应变速率和温度对 Ti45 Al10 Nb合金的屈服强度和延伸率的影响。结果表明 :随着应变速率升高 ,合金的屈服强度升高而延伸率下降 ,由此得到韧脆转变温度 TBDT随应变速率升高而升高的关系 ,并计算出 Ti45 Al10 Nb合金韧脆转变的激活能为 330 k J/ mol。这一数值与 γ- Ti Al合金中原子的自扩散激活能 (2 90 k J/ mol)相当 ,说明Ti45 Al10 Nb合金韧脆转变过程受扩散控制的形变机制 ,即位错攀移控制 ,TEM形貌和断口分析也证明这一结论。

The effects of strain rate and temperature on the tensile yield strength and elongation of titanium aluminides are studied. The alloy Ti 45Al 10Nb(at%) has a fully lamellar microstructure. The test results show that the brittle ductile transition(BDT) temperature increases with the increases of strain rate and temperature. The activation energy is 330kJ/mol, which approximates to the self diffusion activation energy of atoms in the TiAl alloy. Fractography and dislocation configuration analyses demonstrate that the brittle ductile transition of the alloy Ti 45Al 10Nb is controlled by dislocation climb.