Ferromagnetism in metastable 304 stainless steel with bcc structure

Authors

J. Childress, The Johns Hopkins University, Baltimore, Maryland
Sy_Hwang Liou, University of Nebraska-LincolnFollow
C.L. Chien, The Johns Hopkins University, Baltimore, Maryland

Date of this Version

November 1988

Comments

Published by American Institute of Physics. J. Appl. Phys. 64, 6059(1988). © 1988 American Institute of Physics. Permission to use. Journal home page = http://jap.aip.org/jap/.

Abstract

We have studied the consequence of structure on the magnetic properties of 304 stainless steel in two distinct crystalline states. Ordinary 304 stainless steel has an fcc structure and is nonmagnetic at room temperature. By using a vapor quenching method, we have fabricated single-phase metastable bcc 304 stainless steel which is strongly ferromagnetic. Films a few µm thick have been made by high-rate sputter deposition onto substrates at room temperature or liquid-nitrogen temperature. Vibrating sample magnetometry and ⁵⁷Fe Mössbauer spectroscopy reveal that the bcc phase has a magnetization of 130 emu/g, due largely to the Fe moment. The Curie temperature is found to be excess of 550 °C. Upon subsequent annealing above 550 °C, the metastable bcc state transforms back into the usual nonmagnetic fcc phase. The changes in the magnetic properties and the structure of these films during the transformation are examined.