Published online by Cambridge University Press: 04 July 2016
The refractory metals are usually referred to as metals which have melting points equal to, or higher than, chromium. A number of these metals, such as chromium, molybdenum, niobium, and tungsten are already being used quite extensively as alloying elements in both ferrous and non-ferrous alloys. Tungsten has been used in the lamp industry for many years, while molybdenum has been used for heating elements and niobium has been of interest in the atomic energy field.
The advancements in design and efficiency of aero engines has been associated with an increase in engine temperature. If this advancement is to continue, it will be necessary for a new family of alloys to be made available to the engineer. The current nickel-base high temperature alloys are now approaching their limit. It is difficult to be precise about these temperatures because the applications in terms of stress vary widely.