Missouri University of Science and Technology researchers are developing materials not currently in existence with the aid of additive manufacturing technology.
The benefit is that these materials are stronger and lighter than conventional ones and may be less expensive and more efficient to manufacture. The researchers call their process "Cyber Manufacturing Technology", and it includes additive manufacturing process modeling, sensor network and seamless process integration.
The materials that result from this cyber manufacturing are known as Structural Amorphous Metals - SAMs. Like other powder-based additive manufacturing techniques, a laser melts blown powder metal that is deposited layer by layer to create objects. The key is to get the cooling rate correct so that the metal is amorphous instead of its natural state of crystalline formation.
The internal structure of SAMs is random, like grains of sand on a beach. Whereas a crystalline metal will break along its orderly cellular structure, an amorphous metal has no pattern and thus will resist breaking. In addition, the smaller the grains, the stronger the metal material. Thus, SAMs are harder, stronger and have more fracture toughness than conventional metals. These materials also tend to have low corrosive properties and high strength.
Another form of materials possible through additive manufacturing are known as Functionally Gradient Materials - FGMs. These materials combine two metals that don’t combine easily, such as stainless steel and titanium or copper and steel.
The benefit is you can obtain properties of the individual metals, such as thermal conductivity and mechanical strength, that might be needed in specific applications, such as an aircraft or spaceship part.
To make the FGMs so that there is, for example, 100% copper on one side and 100% titanium on the other, the two sides have to be blended by using other metals to bridge the gap. When done, the new material, which doesn’t appear in nature, exhibits the traits of copper and titanium.
But because they’re also made through laser melting, they are formed in extreme heat. In this situation, the cooling rate is critical. It is important to fuse the materials before the microstructure formation or chemical reaction.
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Eng. Rami Khalil
Mechanical Design and Production Engineer.