In the molten state, conventional alloys possess an amorphous structure, or liquid-like atomic arrangement. During their cooling process while transitioning to the solid phase, conventional alloys naturally tend to crystallize into regular geometric microstructures, beginning with the chill crystals that start forming on the outer surface. Amorphous alloys, also known as bulk metallic glass (BMGs), are composed around deep melting points, allowing the alloy to be cooled from the liquid state without forming a crystalline structure.
With a lack of weak regions (grain boundaries), bulk metallic glasses manifest a series of unique material properties. The chart below illustrates this concept.
High-quality Liquidmetal alloys depend on a precise balance of constituent elements with very low levels of impurities. Impurities such as oxygen, nitrogen, hydrogen and carbon can act as initiation sites for crystallization during cooling and can result in inferior crystalline parts. When the composition varies too far from specifications, crystallization can occur much more quickly, compromising its unique properties.
Liquidmetal Technologies has partnered with Materion, the world’s leading producer of beryllium-containing alloys and composites, to produce Liquidmetal alloys to stringent requirements. High-purity elements are melted in large batches in a vacuum induction melting system (VIM) that combines constituent elements by liquefying and stirring them with a high-frequency magnetic field. Once fully alloyed it is then molded into ingots that can be fed directly into our proprietary Liquidmetal Injection Molding process.
Every alloy lot is chemically analyzed to verify that its composition and levels of impurities are within specified limits. Parts are then molded and mechanically tested from every lot to ensure that customer parts will perform to specifications, as described in our data sheet. The Liquidmetal injection molding process is performed under vacuum and induction heating to minimize surface contact between molten metal and the molding apparatus. This prevents oxidization and potential for contamination from foreign material.