Molybdenum 8wt% rhenium alloy processed by laser powder bed fusion: From powder production to mechanical testing at elevated temperatures

Molybdenum is highly valued in industry because of its unique properties, especially at high temperatures. Additive manufacturing technologies, particularly laser powder bed fusion (LPBF), are becoming increasingly popular for producing complex shapes at a lower cost as compared to the conventional forming processes. However, printing molybdenum with LPBF presents challenges, especially caused by its hot cracking susceptibility. Several approaches have been explored to address this issue, including alloying molybdenum with other elements, which has proven effective in enhancing the printability and minimizing the occurrence of cracking, particularly with the addition of rhenium. In this study, a combination of mechanical blending of molybdenum powder and a rhenium precursor, followed by the reduction of the precursor and plasma spheroidization, was used to produce spherical 30–55 μm molybdenum‑rhenium (8 wt%) powders with rheological properties suitable for LPBF. Compared to pure molybdenum, the use of the alloyed powder led to an increase in the crack-free printed density, from 97 to 98.5 %, and in the compressive strength, from 240 to 340 MPa, at 600 °C and from 150 to 190 MPa at 1000 °C, at the expense of a ∼ 5 % reduction in the compression strain. To demonstrate the potential of printing complex geometries using the developed powders, complex geometry artifacts containing 0.25 mm-thin letters, wide dense sections and auto-supported 50 %-density 0.7 mm-thin strut diamond lattice structures were successfully printed.