Metallic glass popped up in the comments following our article about rapid prototyping and I thought I'd look into it since it was new to me and sounded like something quite a few of you would like to know about, too. Things are advancing so fast now, it's hard to keep up, but this is another technology worth understanding because it might have some pretty interesting uses in manufacturing.
Here's the quick rundown:
- Stronger than steel or titanium
- 20 times harder than plastic but can be injection molded like plastic
- Quickly heat the metallic glass with an electrical pulse to its liquid state (550 degrees C)
- Mold and cool before it can crystallize like metal
The heating to the liquid state is done really fast (at a rate of a million degrees per second) using a process called ohmic heating, utilizing a short but intense electrical pulse (1000 joules in one millisecond) which brings the metallic glass up to temperature in half a millisecond. A few milliseconds later it is injection molded and cooled before it can crystallize, retaining the hardness of glass with the toughness of metal. You get the economics of plastic manufacturing applied to metal parts. The new process is called "rapid discharge forming."
The speed of heating and cooling is the key, if it takes too long, the metallic glass forms a crystalline structure before the process is complete.
Since this is a new process, it's unclear what limitations there might be, but as with rapid prototyping, once engineers and designers see how this can be applied, they may be able to focus design decisions on their ideal form instead of on economics or manufacturing feasibility.
Technology is changing directions so fast you have to wear a seatbelt just to read about it. I love it!