This article discusses the characterization of gray iron structures, following the sequence of structure formation, as it applies to unalloyed or low-alloyed gray iron. Austenite grains are the basic crystallographic entities of the metallic matrix in gray cast iron precipitated from the liquid melt. The article describes the macrostructure and dendrite morphology of primary austenite. Eutectoid transformation in the solid state causes the transformation of austenite to pearlite and/or ferrite, producing the as-cast structure. The article discusses the observations of the graphite and ferritic/pearlitic structure in as-cast gray iron.

Malleable iron, like ductile iron, possesses considerable ductility and toughness because of its combination of nodular graphite and low-carbon metallic matrix. There are two basic types of malleable iron: blackheart and whiteheart. This article focuses on the blackheart malleable iron and discusses the chemical composition of malleable iron. A summary of mechanical properties and specifications of malleable iron castings is presented in a table. The article also reviews the mechanical properties of ferritic malleable iron and pearlitic and martensitic-pearlitic malleable irons.

Metallic matrices are essential constituents for the fabrication of metal-matrix composites (MMCs). This article describes three different classes of aluminum alloys, namely, commercial aluminum alloys, low-density and high-modulus alloys, and high temperature alloys. It presents typical tensile properties and fracture toughness of the selected heat treatable aluminum alloys in a table. Titanium alloys are very attractive for MMC applications, due to their higher strength and temperature capability compared to aluminum alloys. The article tabulates the effect of heat treatment on room-temperature properties and tensile properties of Ti-25Al-17Nb alloy sheet.