Large low-field magnetostriction in Fe–W and Fe–Mo alloy single crystals

Fe–Mo and F–W alloys can exist as a single bcc terminal solid solution phase with appreciable Mo and W contents. In this work, the influence of Mo and W additions on the magnetostriction coefficient (3∕2)λ100, elastic constants (C11, C12, and C44), and the magnetomechanical coefficient (B1) of alpha-Fe is examined using alpha-phase Fe–Mo and Fe–W alloy single crystals. Single crystals of Fe–xat.% Mo (x=15,17.5,20) and Fe–xat.% W (x=4.4,10) were grown using the vertical Bridgman technique. Magnetostriction measurements were performed using [100]-oriented and [110]-oriented single crystals. Single crystal elastic constants were determined using resonant ultrasound spectroscopy and analysis technique and [100]-oriented single crystal samples. It is shown that large enhancements in magnetostriction and magnetoelastic coupling constants can be obtained with Mo and W additions. On a per atom addition basis, W additions to Fe provide a larger increase in magnetostriction compared to any other non-rare-earth addition that has been examined with the exception of Ga.