Niobium Clad Neodymium in Wire and Strip Form for Use as a Regenerator
Neodymium is a regenerator material used in Gifford-McMahon cryocoolers at temperatures <10 K due to its high heat capacity resulting from the magnetic order transformation at the Curie temperature. Typically the Nd is used as a powder or small spheres, but it is preferable to use alternative configurations that allow more efficient gas flow and heat transfer. However Nd is difficult to fabricate into wire or strips because it work hardens rapidly and also has a high affinity for oxygen. By cladding the Nd with niobium, it is possible to protect the Nd from oxidation and allow drawing and rolling to small dimensions. This work reports on the development of a process to form Nb clad Nd into fine wire, rolling the fine wire to strip, and the forming of small ridges in the strip. The strip is then wound into a pancake coil, and stacked for use in a regenerator.
KeywordsVoid Fraction Wire Drawing Fine Wire Copper Removal High Heat Capacity
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