Promoting martensitic transformation in Fe-Ni nanoparticles prepared by a Sol-gel and Reduction method

Martensitic transformation (MT) start temperature of the Fe-33Ni nanoparticles prepared by a Sol-gel and Reduction method was found to be higher than that of bulk specimens with the same composition, which is in contrast to the suppressing MT behaviors of nanoparticles in the previous works. Pre-existing bcc phase and polycrystalline structure were confirmed to assist MT in the Fe-33Ni nanoparticles. The mechanism associated with the promotion effect of the pre-existing bcc phase and the grain boundary on MT is discussed.