Video: Controlling Microstructure to Vary Material Properties in AM

How far does the design freedom of additive manufacturing go? We typically think of this in terms of geometric freedom, with additive making it easy to grow components with complex external and internal forms. Then there is material freedom, as additive makes it practical to work with certain metals that would be difficult to use any other way.

But what about microstructure freedom?

ITRI, the Industrial Technology Research Institute in Taiwan, is showing that additive can be used to vary the microstructure in different regions of the same part in order to vary that part’s properties. The institute produced the video above to explain its “Optical Engine” for controlling material grain microstructure.

The Optical Engine relies on a complex shape of the laser beam, ITRI says. A major beam shape melts the powder, while an extended beam shape controls solidification temperatures. Control over preheating temperature and the cooling rate contributes to control over material grains.

Examples of how this capability might be used include an orthopedic component in which a portion of the part needs to resist wear, while another region of the same part needs toughness instead. Tailoring the microstructure could allow this same part to deliver these different properties where needed. Similarly, a turbine rotor could be grown with an isometric material structure at the hub to resist abrasion, and isotropic crystals at the blades to resist high-temperature fatigue.

ITRI is a government-supported organization active in various industries and various technologies. The institute is also working with Taiwanese companies to develop locally manufactured metal additive machines. ​