On the Process Optimization, Microstructure Evolution, and Mechanical Properties of Cucrzr Produced by Laser Directed Energy Deposition

Abstract

Laser Directed Energy Deposition (LDED) is a suitable manufacturing technology for processing CuCrZr alloy that has recently gained interest to be used in high heat flux applications due to its unique thermal properties. However, the low laser absorptivity of this alloy at the laser wavelength of 1060 nm and high thermal conductivity make it challenging to reach a successful deposition. This study reports a systematic investigation into the LDED processing of CuCrZr alloy. The effects of main process parameters, which are laser power, scanning speed, and powder feed rate on the geometry, microstructure, and microhardness of single tracks are studied. Process parameters are optimized to achieve acceptable track geometries that consists of proper bead shape and sufficient dilution as well as maximizing the deposition rate. Further, the results from the investigations on microstructure of the printed samples by optical microscopy, SEM, and EBSD methods show a realistic correlation between the microstructure and the process parameters. Laser power and a combined parameter of powder feed rate over scanning speed are found to play a key role in the grain structure morphology and nucleation. Finally, the microhardness results reveal a moderate transition of hardness from the top of the bead to the bottom of the melt pool for all samples.

Keywords: Additive manufacturing, Laser directed energy deposition, CuCrZr alloy, Process parameters optimization, Grain morphology, Microhardness