Use of Calcium in Alloys: From Modifying to Alloying

Аннотация

Calcium is one of the most widespread and, consequently, low-cost metals on Earth. It has been applied for a long time in modifying and alloying alloys of heavy metals, in particular, lead and copper. It is used as a modifier in cast irons and steels. Calcium began being applied for alloying light alloys based on aluminum and magnesium comparatively recently. In this review, the application fields of metallic calcium and its influence on the structure and properties of various alloys are considered. Alloys based on aluminum–calcium eutectic have been systematically investigated over last few years, and it has been established that they possess casting properties no worse than these of silumins, and they can be hot-rolled and cold-rolled with a high degree of deformation. Ternary and more complex phase diagrams of systems including calcium are constructed and multicomponent alloys based on them are investigated. All these circumstances make it possible to outline several groups of new promising Ca-containing aluminum alloys: (i) alloys hardening without quenching due to the isolation of nanodimensional particles of Al₃Zr, Al₃Sc, and Al₃(Zr,Sc) phases; (ii) high-strength alloys alloyed with traditional hardening elements of the aluminum solid solution, such as zinc and magnesium; and (iii) composite alloys having more than 20% eutectic intermetallic compounds in the structure. All these materials have reduced density, an improved set of operational properties, increased corrosion resistance, and high manufacturability when producing cast and deformed half-finished products.