Lecture 6: Nonferrous alloys

Steel and other ferrous alloys are consumed in exceedingly large quantities because
they have such a wide range of mechanical properties, may be fabricated with relative ease, and are economical to produce. However, they have some distinct limitations chiefly (1) a relatively high density, (2) a comparatively low electrical conductivity, and (3) an inherent susceptibility to corrosion in some common environments. Thus,
for many applications it is advantageous or even necessary to use other alloys that
have more suitable property combinations. Alloy systems are classified either according to the base metal or according to some specific characteristic that a group
of alloys share. This section discusses the following metal and alloy systems: copper,
aluminum, magnesium, and titanium alloys; the refractory metals; the superalloys;
the noble metals; and miscellaneous alloys, including those that have nickel, lead, tin, zirconium, and zinc as base metals. On occasion, a distinction is made between cast and wrought alloys. Alloys that are so brittle that forming or shaping by appreciable deformation is not possible ordinarily are cast; these are classified as cast alloys. On the other hand, those that are amenable to mechanical deformation are termed wrought alloys. In addition, the heat-treatability of an alloy system is mentioned frequently. “Heat-treatable” designates an alloy whose mechanical strength is improved by precipitation hardening or a martensitic transformation (normally the former), both of which involve specific heat-treating procedures.
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