Effective absorptivity of diamond-reinforced metal matrix composites for powder bed fusion using a laser beam

Fabricating diamond-reinforced metal matrix composites through powder bed fusion is an innovative approach for creating abrasive tools with elaborate geometric features. Setting up a stable and reproducible process demands an in-depth understanding of the transient thermal system. The addition of reinforcement particles significantly alters the processing behavior. Furthermore, diamonds are susceptible to thermal degradation, which necessitates careful process development to avoid overheating. Laser absorption has an especially strong impact on the decisive local peak temperatures. Therefore, a calorimetric in-situ method for measuring a material-specific effective absorptivity is adapted. The setup is modified to measure multiple layers, which makes it possible to account for the effective powder layer heights that develop during the process. The results show the effect of different diamond fractions on the absorbed energy. The findings are validated through light microscopy as well as in-situ high-speed camera imaging of single tracks, and their meaning for future research on diamond reinforced metal matrix composites is discussed.