Abstract

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Title:: Strengthening and Toughening Metal Matrix Composites via Transformation Engineering

Author(s):: ZHENG Wangshu; JIA Shuangyue; ZHAO Lei; GUO Qiang; ZHANG Di; 1. State Key Lab of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai, 200240, P.R. China 2. School of Materials Science and Engineering, Nanyang Technological University, 639798, Republic of Singapore

Keywords:: Metal matrix composites; Phase-transforming ceramics; Martensite; Transformation engineering; Strengthening and toughening

Abstract:: The strength-toughness trade-off has long been a research gap constraining the development of metal matrix composites. As a class of reinforcements with excellent intrinsic mechanical properties and deformability, phase-transforming ceramics can undergo reversible phase transformations between austenite (tetragonal phase) and martensite (monoclinic phase) under the stimuli of temperature or stress fields. The associated ~10% lattice strain is expected to alleviate strain localization and stress concentration at the composite interface, thereby achieving a synergistic enhancement of both strength and toughness. On this basis, this paper reviews the research progress on phase-transforming ceramics and their composites by domestic and international researchers. Furthermore, drawing on recent advances made by our team in the field of phase-transforming ceramic-metal matrix composites, we propose a transformation engineering strategy for metal matrix composites. Specifically, we elucidate the challenges, thermodynamic models, and mechanisms of metastability engineering design, thereby establishing general design principles for austenite metastabilization in composites. By triggering the phase transformation of constrained ceramics, we establish and reveal the pathways and mechanisms for strengthening and toughening in the composites. Finally, we summarize the challenges of transforming engineering in metal matrix composites and propose future outlooks.