Direct laser deposition of alloys from elemental powder blends

The complexity in design of components used in advanced aerospace and automotive applications is continuously increasing. This has led to the development of near-net shape manufacturing techniques such as laser engineered net-shaping (LENS TM) which falls in the class of direct laser deposition processes from powder feedstock. Despite considerable advances in process optimization, there is a rather limited understanding of the role of metallurgical factors in laser deposition of alloys. This paper discusses the significant role played by the thermodynamic enthalpy of mixing in the deposition of alloys from elemental powder blends using LENS TM. This factor influences the homogeneity as well as the rate of solidification of the alloy and consequently the microstructure and properties of the deposit. The enthalpy of mixing could also serve as a very useful guideline in the design of novel alloys that are laser deposited from elemental powder blends.