Repeated crack healing in MAX-phase ceramics revealed by 4D in situ synchrotron X-ray tomographic microscopy

• Published in: Scientific reports Vol. 6; no. 1; p. 23040
• Main Authors: 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.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 14.03.2016; Nature Publishing Group
• Subjects: 639/166/984; 639/301/1023/1024; Ceramics; Cracks; High temperature; Humanities and Social Sciences; Mechanical properties; Microscopy; multidisciplinary; Science; Temperature effects
• ISSN: 2045-2322; 2045-2322
• 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 Ti 2 AlC 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 Ti 2 AlC 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.