Any progress on interesting materials (read: not plastic) is welcome news.

Researchers have developed a 3D printing process that transitions from one metal or alloy to another in a single object. For example, they created a prototype of an improved telescope mirror mount. The part at the top near the glass mirror is made of a metal with low thermal expansion, so that it won’t shrink in space as much as most metals do. That prevents stress in the epoxy adhesive between the mirror and the metal. The bottom part of this mount is stronger stainless steel and could be connected to a stainless steel component of a spacecraft.

2023-04-04: Controlling the cooling is crucial to avoid weaknesses

While the printing process wastes less material and can be used to produce more complicated shapes than traditional manufacturing methods, researchers have struggled to grasp how to steer metal toward particular kinds of crystals over others.

This lack of knowledge has led to parts with complex shapes cracking prematurely thanks to their crystal structure. “Among the 1000s of alloys that are commonly manufactured, only a handful can be made using additive manufacturing”. The data depicted the push and pull between 2 kinds of crystal structures, austenite and delta ferrite, the latter being associated with cracking in printed parts. As cooling rates surpassed 1.5m kelvins per second, austenite began to dominate its rival. This critical threshold lined up with what the model foretold. The model can inform what cooling rates to select for the early solidification steps of the printing process. That way the optimal crystal structure would appear within their desired material, making metal 3D printing less of a roll of the dice.

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