Neutron diffraction study on martensitic transformation under compressive stress in an ordered Fe3Pt

Abstract

We have studied the structure change of an ordered Fe3Pt (degree of order ∼0.75) under a compressive stress applied in the [001] direction by neutron diffraction. In the absence of the stress, the alloy exhibits a weak first order martensitic transformation at 90\u2009K from the L12-type cubic structure to the L60-type tetragonal structure. Under the compressive stress of 100\u2009MPa, the first order nature of the thermally-induced martensitic transformation was undetectable in the temperature range of between 70\u2009K and 270\u2009K. The first order nature of the stress-induced martensitic transformation was also undetectable in the stress range of between 6\u2009MPa and 300\u2009MPa when tested at 120\u2009K and higher temperatures. Under these conditions, the lattice parameters change continuously both in the cooling process and in the stress-applying process. Despite the disappearance of the first order nature of martensitic transformation, a significant stress-induced softening of lattice, which is regarded as a precursor phenomenon of martensitic transformation, was observed between 120\u2009K and 265\u2009K but not at 93\u2009K and 295\u2009K.We have studied the structure change of an ordered Fe3Pt (degree of order ∼0.75) under a compressive stress applied in the [001] direction by neutron diffraction. In the absence of the stress, the alloy exhibits a weak first order martensitic transformation at 90\u2009K from the L12-type cubic structure to the L60-type tetragonal structure. Under the compressive stress of 100\u2009MPa, the first order nature of the thermally-induced martensitic transformation was undetectable in the temperature range of between 70\u2009K and 270\u2009K. The first order nature of the stress-induced martensitic transformation was also undetectable in the stress range of between 6\u2009MPa and 300\u2009MPa when tested at 120\u2009K and higher temperatures. Under these conditions, the lattice parameters change continuously both in the cooling process and in the stress-applying process. Despite the disappearance of the first order nature of martensitic transformation, a significant stress-induced softening of lattice, which is regarded as a precursor phenomenon...