Refractory metals are a class of metals that are extraordinarily resistant to heat and wear. The expression is mostly used in the context of materials science, metallurgy and engineering. The definition of which elements belong to this group differs. The most common definition includes five elements: two of the fifth period (niobium and molybdenum) and three of the sixth period (tantalum, tungsten, and rhenium). They all share some properties, including a melting point above 2000 °C and high hardness at room temperature. They are chemically inert and have a relatively high density. Their high melting points make powder metallurgy the method of choice for fabricating components from these metals. Some of their applications include tools to work metals at high temperatures, wire filaments, casting molds, and chemical reaction vessels in corrosive environments. Partly due to the high melting point, refractory metals are stable against creep deformation to very high temperatures.
Other articles related to "refractory metals":
... Refractory metals and alloys attract the attention of investigators because of their remarkable properties and on account of promising practical prospects ... Physical properties of refractory metals, such as molybdenum, tantalum and tungsten, their strength, and high-temperature stability make them suitable material ... at high-temperatures are shortcomings of most refractory metals ...
Famous quotes containing the word metals:
“As in digging for precious metals in the mines, much earthy rubbish has first to be troublesomely handled and thrown out; so, in digging in ones soul for the fine gold of genius, much dullness and common-place is first brought to light.”
—Herman Melville (18191891)