The magnetocaloric effect, magnetic refrigeration and ductile intermetallic compounds

The magnetocaloric effect (MCE) is the ability of a magnetic material. particularly near its Curie temperature,. to heat LIP when a magnetic field is applied (magnetization) and to cool when the field is removed (demagnetization). A number of new materials, especially Gd-5(Si4-xGex), have outstanding MCE properties near room temperature, significantly better than the well-known standard, Gd metal. The giant MCE effect observed in the Gd-5(Si4-xGex) alloys for x >= 2 is due to a coupled magnetostructural transformation. The coupled transformation also accounts for several other interesting phenomena: giant magnetoresistance; colossal magnetostriction, spontaneous generation of voltage; unusual training, dynamical and thermal phenomena; acoustic emissions; and a novel glass-like kinetically retarded state. Extension of the work on the MCE has led to the near commercialization of magnetic refrigeration as a viable cooling technology, and to the discovery of ductile rare earth transition metal (RM) B2 CsCl-type intermetallic compounds. (C) 2008 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.