Laser Engineered Net Shaping (LENS^®) is a solid freeform fabrication (SFF) technology that combines high power laser deposition and powder metallurgy technologies. The LENS^® technology has been used to fabricate a number of metallic alloys with improved physical and mechanical material properties. The successful application provides a motivation to also apply this method to fabricate non-metallic alloys, such as tungsten carbide-cobalt (WC-Co) cermets in a timely and easy way. However, reports on this topic are very limited. In this work, the LENS^® technology was used to investigate its application to nanostructured WC-Co cermets, including processing conditions, microstructural evolution, thermal behavior, mechanical properties, and environmental and economic benefits. Details of the approaches are described as follows.

A comprehensive analysis of the relationships between process parameters, microstructural evolution and mechanical properties was conducted through various analytical techniques. Effects of process parameters on sample profiles and microstructures were analyzed. Dissolution, shape change and coarsening of WC particles were investigated to study the mechanisms of microstructural evolution. The thermal features were correlated with the microstructure and mechanical properties.

The special thermal behavior during this process and its relevant effects on the microstructure have been experimentally studied and numerically simulated. A high-speed digital camera was applied to study the temperature profile, temperature gradient and cooling rate in and near the molten pool. Numerical modeling was employed for 3D samples using finite element method with ADINA software for the first time. The validated modeling results were used to interpret microstructural evolution and thermal history.

In order to fully evaluate the capability of the LENS^® technology for the fabrication of cermets, material properties of WC-Co cermets produced by different powder metallurgy technologies were compared. In addition, another cermet system, nanostructured titanium/tungsten carbide-nickel ((Ti,W)C-Ni) powder, prepared using high-energy ball milling process, was also deposited by the LENS^® technology.

Because of the near net shape feature of the LENS^® process, special emphasis was also placed on its potential environmental and economic benefits by applying life cycle assessment (LCA) and technical cost modeling (TCM). Comparisons were conducted between the conventional powder metallurgy processes and the LENS^® process.