Engineering materials lightweight metals

Froes F H, Kim Y and Krishnamurthy S (1989), Rapid solidification of lightweight metal alloys . Materials Science and Engineering, 117, 19-32. 

Appllca.tlons. The principal appHcations of nickel-base superalloys are in gas turbines, where they are utilized as blades, disks, and sheet metal parts. Abcraft gas turbines utilized in both commercial and military service depend upon superalloys for parts exposed to peak metal temperatures in excess of 1000°C. Typical gas turbine engines produced in the United States in 1990 utilized nickel and cobalt-base superalloys for 46% of total engine weight (41). However, programs for future aerospace propulsion systems emphasize the need for lightweight materials having greater heat resistance. For such apphcations, intermetallics matrix composites and ceramic composites are expected to be needed. 

The field of aeronautics, the automobile industry, and also in many areas of the engineering, the demand for lightweight components leads to the adaption of materials having a very low specific weight. Light metal alloys are not often used because they have some drawbacks such as a low stiffness, high thermal expansion coefficient, and low wear resistance. However, the combinations of the alloys with other materials can improve the mechanical as well as their thermal properties. 

Polymers serve increasingly in structural applications as lightweight replacements for more traditional materials such as metals and wood. In light of this it is important to understand and be able to characterize the engineering or mechanical properties over the likely service conditions (see Mechanical Performance OF Plastics). Typically when a material fails in service it is thought of in terms of a catastrophic brittle failure and these modes have been partially discussed elsewhere (see Fatigue). However, polymers (both thermoplastics and... 

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