Grant: Discovery Grants Program - Individual

To tackle the rapidly evolving energy crisis and achieve the goal of net-zero emissions in Canada's transportation industry, lightweighting is one of the key strategies for increasing energy efficiency and long-term sustainability. As such, advanced lightweight materials are urgently needed. In alloy design, an exciting new concept of high-entropy alloys that involves the combination of multiple principal elements has been proposed. The search for high-entropy alloys is now at the forefront of materials science, being described as "taking the field of materials science by storm" or "a burgeoning field of metallurgy." This novel approach represents a paradigm shift from the conventional alloy design of a single principal element with small amounts of alloying elements, offering a vast composition space and bringing a previously unexplored pathway for developing advanced materials with promising properties for lightweight structural applications. However, given its short history relative to the conventional alloys, the field of high-entropy alloys is still in its infancy. There are many fundamental issues that challenge the established materials science theories and models, including the formation of different phases, and underlying strengthening and deformation mechanisms in high-entropy alloys. Other questions remain as to how the deformation-induced twinning and phase transformation interact with dislocation slip in a severe lattice distortion situation, and if the addition of light elements (aluminum and titanium) can enhance the strength-ductility synergy and fatigue resistance. The objectives of the proposed research are to address these critical issues and barriers and advance materials science knowledge, building upon the applicant's extensive and pioneering research experience and expertise in this area, and develop a fundamental understanding of fatigue and fracture of lightweight high-entropy alloys. Specifically, the following topics will be examined: i) the underlying fatigue deformation and twinning mechanisms in lightweight high-entropy alloys fabricated mainly via additive manufacturing will be elucidated and modeled, ii) the phase transformation, texture and residual stresses will be analyzed and evaluated using a unique high-temperature X-ray diffractometer which permits in-situ measurements as a function of temperatures, iii) the effect of heat treatment and hot isostatic pressing on fatigue deformation resistance will be examined, and iv) new processing approaches and models will be developed to tweak textures and reduce anisotropy. These projects will advance fundamental understanding of long-term performance in high-entropy alloys, lay a foundation for further development of next-generation lightweight materials for automotive, aerospace and energy applications, and lead to the training of Ph.D. and Master's students who are in high demand from industry, academia, and government laboratories.