Modern Light Alloys and Their Application to Aircraft-Engine Design 290063

A NUMBER of the more important commercial alloys having aluminum as their base are discussed by the author, who points out their main physical characteristics and outlines methods which can be used in their fabrication, indicating in a general way which alloys are best suited to various aircraft-engine requirements. Tables are given showing chemical compositions and physical properties, including a table of physical properties of various casting alloys at elevated temperatures. Special-purpose alloys are commented upon, and also a new aluminum alloy for pistons which is beginning to find commercial application and possesses properties particularly desirable in aircraft engines.

Recent developments in magnesium alloys and their application to aircraft-engine design are specified, tables of physical properties are given, and comments are made on the characteristics of the material as compared with aluminum alloys. It is believed that, for certain applications in which strength and weight-saving are the main considerations, magnesium alloys will find wide application, although the author recommends thorough tests before adopting magnesium for major engine-parts.

It is stated in the discussion that the magnesium alloys, particularly the aluminum-manganese-magnesium alloys, are the equal of 195 casting alloy in corrosion resistance and therefore are placed in Class C. Corrosion, being a surface phenomenon, has less importance in the case of thick than of thin castings. Corrosion of magnesium castings for aircraft engines usually is caused by difficulties that can be corrected, such as the use of gasket material containing corrosive elements, rather than by ordinary atmospheric conditions. Regarding permanent-mold castings, it is said to be possible to produce fairly large and intricate castings by this process, provided they are laid out with a view to such production.