Effect of Hydrostatic Pressure on Martensitic Transformations in Fe–Ni and Fe–Ni–C Alloys

• Published in: Transactions of the Japan Institute of Metals Vol. 29; no. 2; pp. 109 - 115
• Main Authors: Kakeshita, Tomoyuki, Shimizu, Ken’ichi, Akahama, Yuichi, Endo, Shoichi, Fujita, Francisco Eiichi
• Format: Journal Article
• Language: English
• Published: Sendai The Japan Institute of Metals 1988; Japan Institute of Metals
• Subjects: Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; hydrostatic pressure; iron-nickel alloy; iron-nickel-carbon alloy; martensite amount; martensite morphology; martensitic transformation; Materials science; Metals, semimetals and alloys; Phase diagrams and microstructures developed by solidification and solid-solid phase transformations; Physics; Specific materials; transformation temperature; Thermodynamics; Optical microscopy; Examination method; Electrical conductivity; Pressure effect; Magnetization; Transition metal Alloys; Morphology; Hydrostatic pressure; Martensitic transformation; Experimental study; Martensite
• ISSN: 0021-4434; 2432-4701
• DOI: 10.2320/matertrans1960.29.109

Effects of hydrostatic pressure on martensitic transformations in Fe-29.9Ni and Fe-24.6Ni-1.8C (at%) alloys have been investigated by means of electrical resistivity and magnetization measurements and optical microscopy under a pressure of up to 1.5 GPa. As a result, the followings were found: Transformation temperatures under hydrostatic pressure, Ms′, shift from that under no pressure, Ms, and the amount of the shift, ΔMs=Ms−Ms′, increases curvilinearly with increasing hydrostatic pressure. In the increasing manner of ΔMs, however, a considerable difference is recognized between the Invar Fe–Ni alloy and the non-Invar Fe–Ni–C alloy. The amount of the martensites induced at Ms′ decreases with increasing hydrostatic pressure. Morphology of the hydrostatic pressure-induced martensites is the same as that of the thermally-induced ones irrespective of the formation temperature. A thermodynamical analysis for the hydrostatic pressure dependence of the transformation temperature shows that other effects should be taken into consideration besides the effect that the volume expansion associated with the martensitic transformation is opposed to hydrostatic pressure as has previously been proposed.