Shape memory alloys (SMAs) operating as solid-state actuators pose economic and environmental benefits to the aerospace industry due to their lightweight, compact design, which provides potential for reducing fuel emissions and overall operating cost in aeronautical equipment. Despite wide applicability, the implementation of SMA technology into aerospace-related actuator applications is hindered by harsh environmental conditions, which necessitate extremely high or low transformation temperatures. The versatility of the NiTi-based SMA system shows potential for meeting these demanding material constraints, since transformation temperatures in NiTi can be significantly raised or lowered with ternary alloying elements and/or Ni:Ti ratio adjustments. In this thesis, the expansive transformation capabilities of the NiTi-based SMA system are demonstrated with a low and high-temperature NiTi-based SMA; each encompassing different stages of the SMA development process. First, exploratory work on the NiTiSn SMA system is presented. The viability of NiTiSn alloys as low-temperature SMAs (LTSMAs) was investigated over the course of five alloy heats. The site preference of Sn in near-equiatomic NiTi was examined along with the effects of solution annealing, Ni:Ti ratio adjustments, and precipitation strengthening on the thermomechanical properties of NiTiSn LTSMAs. Second, the thermomechanical processability of NiTiHf high-temperature SMA (HTSMA) wires is presented. The evolution of …

In this dissertation, small and large NaCl particle-derived surfaces (Ra > 40 microns) were generated on 2D Zn materials, and the surfaces were carefully studied concerning topography, corrosion behavior, and bone cell compatibility. Increases in surface roughness accelerated the corrosion rate, and cell viability was maintained. This method was then extended to 3D porous scaffolds prepared by a hybrid AM/casting technique. The scaffolds displayed a near-net shape, an interconnected pore structure, increasing porosity paralleled to an increased corrosion rate, an ability to support cell growth, and powerful antibacterial properties. Lastly, nano/micro (Rz 0.02–1 microns) topographies were generated on 2D Zn materials, and the materials were comprehensively studied with special attention devoted to corrosion behavior, biocompatibility, osteogenic differentiation, immune cell response, hemocompatibility, and antibacterial performance. For the first time, the textured nonhemolytic surfaces on Zn were shown to direct cell fate, and the micro-textures promoted bone cell differentiation and directed immune cells away from an inflammatory phenotype.

This work identifies alloy terminal freezing range, columnar growth, grain coarsening, liquid availability towards the terminal stage of solidification, and segregation towards boundaries as primary factors affecting the hot-cracking susceptibility of fusion-based additive manufacturing (F-BAM) processed alloys. Additionally, an integrated computational materials engineering (ICME)-based approach has been formulated to design novel Al alloys, and high entropy alloys for F-BAM processing. The ICME-based approach has led to heterogeneous nucleation-induced grain refinement, terminal eutectic solidification-enabled liquid availability, and segregation-induced coalescence of solidification boundaries during laser-powder bed fusion (L-PBF) processing. In addition to exhibiting a wide crack-free L-PBF processing window, the designed alloys exhibited microstructural heterogeneity and hierarchy (MHH), and thus could leverage the unique process dynamics of L-PBF to produce a fine-tunable MHH and mechanical behavior. Furthermore, alloy chemistry-based fine tuning of the stacking fault energy has led to transformative damage tolerant alloys. Such alloys can shield defects stemming from the stochastic powder bed in L-PBF, and consequently can prevent catastrophic failure despite the solidification defects. A modified materials systems approach that explicitly includes alloy chemistry as a means to modify the printability, properties and performance with F-BAM is also presented. Overall, this work is expected to facilitate application specific manufacture with …