Spangold

Spangold is a family of shape memory-effect alloys (SME) of gold, copper, and aluminum in either 18K or 23K. The name of the family is a play on the word "spangled".[1]

Spangold is a beta-phase alloy with a nominal stoichiometry of Au₇Cu₅Al₄ and a nominal composition by mass of 76% gold, 18% copper, and 6% aluminum. The texture is caused by the induction of a martensitic-type phase transformation on a polished surface.[2][3]

Spangold undergoes a martensitic-type phase transformation when properly treated.^[citation needed] This phase transformation is induced on a polished surface of the alloy.^[citation needed] Martensitic transformations are a common feature in shape memory alloys, and they involve a reversible change in crystal structure that allows the material to recover its original shape when subjected to specific temperature changes.^[citation needed]

References

1. Ira Wolff; Michael Cortie (1994). "The Development of Spangold". Gold Bulletin. 27 (2): 44–54. doi:10.1007/BF03214729.
2. "Spangold Alloys". Total Materia. July 2013.
3. "Spangold : a now aura for Intermetallica". Metal Abstracts. 27: 15. June 1994.