High throughput prototyping and multiscale indentation characterization of metallic alloys

Abstract

Accelerating discovery and deployment of advanced material systems requires moving away from traditional sample prototyping, testing methods, and microstructure characterization techniques. In addition, the hierarchical multiscale structure of advanced materials holds the key to improving their performance characteristics. In order to understand and characterize microscale constituents, and length scale effects, novel high throughput approaches are necessary to explore mechanical responses from nano to meso, and macro scale. Several different techniques exist for testing materials at small length scale, including, microtension, micro-pillar compression, micro- bending, and nanoindentation. Among these, spherical nanoindentation is the most efficient and most reliable one. This high throughput mechanical protocol is capable of capturing local mechanical responses at different length scales in polycrystalline metals in the form of indentation stress-strain curves. These responses can then be correlated to local material structure using modern data-driven approaches. In this work, we are seeking two main goals. First, exploring the viability of high throughput experimental assays for establishing PSP linkages in structural metals, while utilizing small sample volumes and leveraging some of the recent advances described earlier (i.e., spherical microindentation stress-strain protocols and the framework of 2-point statistics). Second, providing detailed insights on mechanical characterization of hierarchical materials and understanding the underlying length scale effects in each constituent phase. For this purpose, the development of the protocols is extended to two advance groups of structural materials with higher levels of microstructural complexity, one represents multiphase polycrystalline group and the other represents composite materials. The multiphase polycrystalline were chosen to be dual-phase (DP steels) where both existing phases, martensite and ferrite, are crystalline but different crystal structures. The composite material is a Ti-based bulk metallic glass matrix composites (BMG-MCs) in which dendrites of a crystalline phase exist in a matrix of amorphous phase. We have selected these alloys in this dissertation because of their importance to several advanced technologies, owing to their excellent combination of high tensile strength and good ductility. The work will have a profound impact on speeding up the process of developing new structural materials by reducing the time and energy spent in mechanical characterization at different length scales and establishing PSP linkages.