|About this Abstract
||MS&T23: Materials Science & Technology
||Interface-mediated Phenomena in Structural Materials
||Localized Phase Transformation (LPT) at Stacking Faults and Twin Boundaries and Their Impact on Properties
||Yuchi Wang, Longsheng Feng, Yipeng Gao, Ashton Egan, Timothy Smith, Hao Tang, Qing-Jie Li, Ju Li, Michael J. Mills, Yunzhi Wang
|On-Site Speaker (Planned)
Through a combination of crystallographic analysis, thermodynamic modeling, MD simulations, and experimental characterization, we have discovered that twin boundaries and stacking faults can serve as sites for the formation of new phases that confer exceptional functional and mechanical properties. In NiTi shape memory alloys and metastable Ti-alloys, we have observed extended deformation twin boundaries with core structures consisting of B2|B19’|B2(twin) sandwich in the former or β|α”|β(twin) sandwich in the latter, resulting in linear superelasticity with an ultra-low modulus and nearly zero hysteresis. In Ni-based superalloys, the localized phases formed at stacking faults and annealing/deformation twin boundaries can be either ordered or disordered, leading to drastically different creep performance. We have established a new criterion based on the relative stability of ordered and disordered stacking fault phases for the design of LPT-strengthened superalloys. By designing a new alloy based on this principle, we have achieved unprecedented creep performance.