Manufacturing of novel metal alloys
20.06.2019 The Institute for Applied Laser, Photonics and Surface Technologies ALPS of Bern University of Applied Sciences (Berner Fachhochschule BFH) has been developing a laser-based process to produce novel metal alloys in seconds. They can be super hard, acid-resistant or ductile. Such alloys can be used e.g. in aerospace industry. The technique that can form those alloys is called laser direct metal deposition or LDMD.
Laser direct metal deposition basically is a cladding process. A laser beam and a powder beam are guided coaxially by a nozzle to the surface of a workpiece such that the powder as well as the surface of the workpiece are molten. A bulk layer of the molten powder metal is generated on the workpiece. The process can be utilized for single-layer depositions as well as for multi-layer applications to generate complex shapes in the sense of Additive Manufacturing, in which objects are created in layers from a 3D-model.
Laser as the key to success
In 3D LDMD, composition and structure of the built-up part can directly be adapted by varying the process parameters. In particular, the alloy can be adjusted by mixing different elemental metal powders in the powder nozzle.
The possibility to create novel alloys by mixing elemental metal powders and adjusting their properties during the process opens doors to new applications. In combination with rapid heating and cooling typical for laser processes, LDMD is able to create new alloys with outstanding properties.
Furthermore, changing the ratio of the elemental metal powders during the process allows for adjusting the material properties locally, e.g. microstructure, hardness or ductility can be modified according to the local requirements. And thanks to high laser power and concentrated energy input this technique works for refractory metals like tungsten and molybdenum as well.
Two metal alloys like nickel aluminides (NiAl, NiAl3 and Ni3Al) with different local properties have successfully been created by means of LDMD.