|About this Abstract
|MS&T23: Materials Science & Technology
|Interface-mediated Phenomena in Structural Materials
|Effects of Phase Boundaries on Enhanced Hardness in a Microstructurally Stable Nanocrystalline Ni-based Alloy
|Mari-Therese Burton, Alicia Koenig, Helen M. Chan, Christopher J. Marvel, Martin P. Harmer
|On-Site Speaker (Planned)
Nanocrystalline materials exhibit superior strength due to their high density of grain boundaries but are unstable against grain growth, limiting their structural and mechanical use. Furthermore, while thermal stability mechanisms have been researched extensively, holistic strategies that limit coarsening in complex alloys beyond model binary and ternary systems still remain unexplored. In this work, a Ni-11at%W-3at%Ta-2at%Y alloy was designed to be stabilized by grain boundary segregation, secondary phase pinning, and Ni(W,Ta) solid solution induced sluggish diffusion. Microstructure/property predictions were experimentally verified: the alloy was synthesized via high-energy mechanical alloying, annealed up to 0.7Tm for 100 hours, and characterized using advanced electron microscopy techniques. Our main observations were that yttria particles kinetically stabilized the alloy, and that enhanced hardness was attributed to the interactions between dislocations and yttria/matrix phase boundaries. Overall, this work has revealed how phase boundary coherency and atomic structure can be leveraged for future structural alloy design principles.