Al-Mg-Sc-Zr alloy processed via laser powder bed fusion (LPBF) is poised for significant application in aerospace, where its high-temperature capabilities are paramount for the safety and longevity of engineered structures. This study offers a systematic examination of the alloy’s high-temperature tensile properties in relation to its microstructure and precipitate phases, utilizing experimental approaches. The LPBF-processed Al-Mg-Sc-Zr alloy features a bimodal microstructure, with columnar grains in the melt pool’s interior and equiaxed grains along its boundary, conferring exceptional properties. The application of well-calibrated processing parameters has yielded an alloy with an impressive relative density of 99.8%, nearly fully dense. Following a thermal treatment of 350 °C for 4 h, the specimens were subjected to tensile tests at both room and elevated temperatures. The data reveal that the specimens exhibit a tensile strength of 560.6 MPa and an elongation of 11.1% at room temperature. A predictable decline in tensile strength with rising temperature is observed: at 100 °C, 150 °C, 200 °C, and 250 °C; the respective strengths and elongations are 435.1 MPa and 25.8%, 269.4 MPa and 20.1%, 102.8 MPa and 47.9%, 54.0 MPa and 72.2%. These findings underpin the technical rationale for employing LPBF-processed Al-Mg-Sc-Zr alloy in aerospace applications.

Aiming at the contradiction between forming quality and efficiency in the existing research on thick-layer laser powder bed fusion (LPBF) manufacturing of Ti6Al4V, this study focused on the influence of near-circular keyhole defects caused by scanning speed on the short-term mechanical properties of Ti6Al4V alloy manufactured by high-efficiency LPBF with a 100 μm layer thickness, the build rate of which reached 14 mm³/s. When the scanning speed decreased to 800 mm/s, the relative density decreased from 99.87% to 99.27%, and the maximum pore size increased from 19.6 μm to 87.2 μm. Under the conditions of high relative density (above 99.8%) and maximum pore size less than 20 μm, the annealed Ti6Al4V samples could achieve a tensile strength of 1009.7 MPa, a yield strength of 914.0 MPa, an elongation of 15.2%, and an impact toughness of 41.71 J/cm². With the increase in porosity and a maximum pore size exceeding 50 μm, the tensile strength became more unstable and exhibited a declining trend, while the impact toughness decreased by more than 5%. This is mainly attributed to the stress concentration around large-sized pores, leading to the easy generation of long and deep cracks at the edges and reducing the material’s ability to resist crack initiation and propagation.

ZGH451 is a novel age-strengthened nickel-based superalloy renowned for its exceptional toughness and corrosion resistance. However, it is susceptible to cracking during laser powder bed fusion (LPBF) processing. This study systematically investigates LPBF-fabricated ZGH451 to establish the inherent relationship between volumetric energy density (VED) and crack evolution, with particular emphasis on crack initiation and propagation mechanisms. Our findings confirm that optimized VED effectively suppresses cracking. Experimental results reveal that VEDs above 70 J/mm ³ induce edge-localized cracks dominated by stress cracks and ductility-dip cracks (DDC), whereas VEDs below 45 J/mm ³ produce surface-distributed fine cracks characterized as solidification/liquation cracks. Microstructural analysis demonstrates two distinct mechanisms: excessive VED facilitates high-angle grain boundary cracking, while Al/Ti-based low-melting eutectic phases and Cr/W/Ta/C-derived carbides synergistically enhance grain boundary embrittlement, thereby creating prerequisites for crack nucleation and growth. Moreover, by adjusting the VED from 100 J/mm ³ to 49.45 J/mm ³ , the grain size is refined from 62.43 µm to 35.83 µm, and the grain boundary density is increased by 42.6 %. These improvements significantly reduce stress concentrations and crack formation. This work establishes fundamental correlations between VED and crack behavior in LPBF-processed ZGH451, providing critical guidance for defect mitigation through controlled energy parameters.