Tensile behaviour of Co–Al–W–Ta–B–Mo alloys with a coherent γ/ γ’ microstructure at room and high temperatures
Tensile behaviour of Co–Al–W–Ta–B–Mo alloys with a coherent γ/ γ’ microstructure at room and high temperatures
复制标题
具有相干 γ/ γ- 微观结构的 Co-Al-W-Ta-B-Mo 合金在室温和高温下的拉伸行为
DOI：
10.1016/j.msea.2015.04.018
复制
发表时间：
2015
期刊：
影响因子：
--
通讯作者：
J. B. Sha
中科院分区：
文献类型：
--
作者：
F. Zhong;S. S. Li;J. B. Sha
The microstructure and tensile behaviour of Mo-doped Co–9Al–(9−x)W–2Ta–0.02B–xMo alloys (wherex=0, 2, and 4 at% is hereafter referred to as 0Mo, 2Mo, and 4Mo alloys, respectively) at room and high temperatures have been investigated. Aged at 800 °C for 100 h, all alloys consist of a Co solid-solution γ-CoSSmatrix and nano-scale cuboidal γ′-Co3(Al, W) intermetallic precipitates. The γ matrix is coherent with the γ′-Co3(Al, W) precipitates. With a coherent γ/γ′-Co3(Al, W) microstructure, the aged alloys show tensile yield strength anomalies at temperatures above 700 °C, and the 0Mo alloy always exhibits the highest strength at 600–800 °C. It is interesting that the alloys also possess anomalously low elongation of 0.4–3.3% at 600–800 °C, which is significantly below the ~10% elongation at room temperature. Intergranular cleavage is found to be the dominant failure mode of the γ/γ′-Co3(Al, W) microstructure at high temperatures, resulting in tensile plasticity anomalies. At room temperature, however, slip bends are observed on the aligned γ and γ′ phases, and the γ/γ′-Co3(Al, W) coherent microstructure fails in a dimple mode with excellent elongation.
