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 5 elements, two of the fifth period, niobium and molybdenum, and three of the sixth period, tantalum, tungsten and rhenium. They all share some properties, for example they all have a melting point above 2000 °C and are hard 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.
Adapted from the Wikipedia article Refractory metals, under the G. N. U. Free Documentation License. Please also see http://en.wikipedia.org/wiki
Refractory metals – Introduction
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.
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