Guessing here, but maybe you are looking for Titanium-Nickel alloy (TiNi)?
If I remember correctly that is what the bows are made of on my glasses. You can bend them almost 90 deg and they will spring back to their original shape. Here is some info from a research project I found:
=== "Tensile Properties and Transformation Temperatures of Ti-Ni Alloy Dental Castings Added Cu
Hisashi Doi, Equo Kobayashi, Takayuki Yoneyama and Hitoshi Hamanaka
Department of Metallurgy, Division of Biomaterials, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University (2-3-10, Kanda-Surugadai, Chiyoda-ku, Tokyo 101-0062) Original Paper: J J Dent Mate Vol. 20 No. 1 48-53 (2001) Keyword: Titanium-nickel alloy, Superelasticity, Mechanical properties
The application of the Ti-Ni base alloy to dentistry is expected to utilize its shape memory effect and super-elasticity properties. The transformation temperature changes when part of the nickel in a Ti-Ni alloy is replaced with copper. In this study, the super-elastic property of Ti-Ni alloy in which part of the nickel was replaced with
10mol% of copper was investigated, and the application of this alloy to dental casting was also examined. The results of this study showed that the super-elasticity of dental casted Ti-Ni-Cu alloy with 10mol% of replacement copper was good and that this maybe a useful method of reducing the quantity of nickel in Ti-Ni based alloy." ===
From Mat-world:
Titanium Nickel Alloy TiNi Alloy Ti-Ni (50:50 wt%) Ingots, Wires, Sputtering Target, Sheet, Plate, Disk
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Maybe this is the stuff you are looking for or could use...