Because of stringent performance specifications, alloys included in the category of nickel-base superalloys are some of the most metallurgically complex and expensive in the field of metallurgy. The fact that these complex alloys can be manufactured commercially to make reliable components reflects the skill which alloy producers apply to control composition to meet rigid specification of trace elements as well as alloy constituents. Nevertheless, a substantial amount of scrap is used in the manufacture of these alloys, and highly specialized operations have been developed to process this scrap. This paper provides an overview of the current use of scrap in the industry and procedures for handling, melting, and refining scrap. The effects of residual elements commonly encountered in superalloy scrap on structure and properties are reviewed. Finally, a brief assessment of trends in generation and use of scrap is presented.

Source: J. J. deBarbadillo. "Nickel-base superalloys; physical metallurgy of recycling". Met. Trans. A. Vol. 14. No. 2. February, 1983. Pp. 329-341.
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