In this study, we fabricated an Al-Ni-Zr alloy using laser powder bed fusion (PBF-LB), and systematically investigated its processability, microstructural development process, and the relationship between the microstructures and mechanical properties. Cracks originated from delamination were generated in the PBF-LB specimen along melt pool boundaries under preheating at 35°C, meanwhile preheating at 200°C could avoid the cracks due to suppression of thermal stress/distortion. The as-built PBF-LB specimen had a high relative density of greater than 99.9% and exhibited extremely excellent room-temperature strength, which is comparable to that of a heat-treated ultra-super duralumin. The PBF-LB specimen consisted of bimodal crystal grains with fine equiaxed and columnar morphology, owing to heterogeneous nucleation by the primary crystallized Al₃Zr phase, which has crystallographic coherency with an α -Al matrix phase. Nickel solute element was crystallized at cell boundaries to form α-Al/Al₃Ni eutectic phase. Meanwhile, zirconium and nickel solute elements were partially dissolved in the α-Al solid solution due to rapid solidification by laser melting. Microstructural observation results suggested that the major strengthening factors for the Al-Ni-Zr PBF-LB specimens should be grain refinement strengthening by the fine bimodal crystal grains and dispersion strengthening by the Al₃Zr phase.

Commercially pure titanium rolled sheets with different grain sizes of 20, 50 and 80 μm were applied to tensile tests to investigate the effects of grain size on the relationship between mechanical properties and activities of slip systems. While the ductility was independent of grain size, the activity of first order pyramidal slips and second order pyramidal slips decreased with decreasing grain size. In addition, grain boundary sliding was found to contribute to ductility when the grain size was small. Prismatic slips were activated in all of the specimens when yielded. Activity of pyramidal slips increased with increasing strain and decreased with decreasing grain size. Tensile tests were interrupted and slip lines were observed after the unloading in this study. Yield stress increment was observed when reloaded in interrupt tensile tests, but not in immediate reloading tensile tests. We found room temperature strain aging in pure titanium sheets. Yield stress increment increased with increasing strain.