SLM techniques could enable manufacture of complex parts

By experimenting with various blends of relatively cheap, coarse powders, the team at Exeter University was able to create extremely hard metal matrix composites with underlying reinforcing microstructures.

SLM essentially involves a laser that scans back and forth over the surface of a powder, melting it in the shape of the first layer. The work surface then drops by the thickness of the layer and another layer of powder is distributed over the surface.

Generally, research has focused on blending extremely fine (and expensive) powders before sintering to achieve novel components. The research team at Exeter, however, began experimenting in a trial-and-error fashion with various aluminium alloys mixed with iron oxide.

‘Although we use a mixture of relatively coarse and cheap powders, the laser-assisted chemical reaction allows the production of new constituents that are different from primary ones,’ Dr Sasan Dadbakhsh of Exeter told The Engineer. ‘These new constituents have been formed under laser rapid solidification, which abundantly restricts their growth, leading to their ultrafine and nanoscale sizes.’