Refractory metals are a specific group of elements, primarily niobium, molybdenum, tantalum, tungsten, and rhenium, known for their exceptionally high melting points and hardness at elevated temperatures. They are used to make furnace components, high-speed cutting tools, and aerospace alloys. Because they oxidize rapidly at high heat, they often must be processed in a vacuum or inert atmosphere.
Heard on the job
We use refractory metal shielding in the vacuum furnace because standard steel would melt at those cycle temperatures.