Sloof Willem G, Pei Ruizhi, McDonald Samuel A, Fife Julie L, Shen Lu, Boatemaa Linda, Farle Ann-Sophie, Yan Kun, Zhang Xun, van der Zwaag Sybrand, Lee Peter D, Withers Philip J
Department of Materials Science and Engineering, Delft University of Technology, Mekelweg 2, 2628 CD, Delft, The Netherlands.
School of Materials, Manchester University M13 9PL, UK.
Sci Rep. 2016 Mar 14;6:23040. doi: 10.1038/srep23040.
MAX phase materials are emerging as attractive engineering materials in applications where the material is exposed to severe thermal and mechanical conditions in an oxidative environment. The Ti2AlC MAX phase possesses attractive thermomechanical properties even beyond a temperature of 1000 K. An attractive feature of this material is its capacity for the autonomous healing of cracks when operating at high temperatures. Coupling a specialized thermomechanical setup to a synchrotron X-ray tomographic microscopy endstation at the TOMCAT beamline, we captured the temporal evolution of local crack opening and healing during multiple cracking and autonomous repair cycles at a temperature of 1500 K. For the first time, the rate and position dependence of crack repair in pristine Ti2AlC material and in previously healed cracks has been quantified. Our results demonstrate that healed cracks can have sufficient mechanical integrity to make subsequent cracks form elsewhere upon reloading after healing.
MAX相材料正成为有吸引力的工程材料，适用于材料在氧化环境中承受严苛热和机械条件的应用场景。Ti2AlC MAX相即使在超过1000 K的温度下仍具有吸引人的热机械性能。这种材料的一个吸引人的特性是其在高温运行时能够自主修复裂纹。我们将一个专门的热机械装置与TOMCAT光束线的同步加速器X射线断层扫描显微镜终端站相结合，在1500 K的温度下，捕捉了多个裂纹和自主修复循环过程中局部裂纹张开和愈合的时间演变。首次对原始Ti2AlC材料以及先前愈合裂纹中的裂纹修复速率和位置依赖性进行了量化。我们的结果表明，愈合后的裂纹能够具有足够的机械完整性，使得在愈合后重新加载时，后续裂纹会在其他地方形成。
