Effect of [gamma] [leftrightarrow] [epsilon] cyclic transformations on the shape memory characteristics of an Fe-Mn-Si-Cr-Ni alloy

Journal Article · Fri Apr 01 04:00:00 EST 1994 · Materials Characterization; (United States)

DOI:https://doi.org/10.1016/1044-5803(94)90092-2· OSTI ID:7289458

Ohtsuka, H; Kajiware, S; Ishihara, T ^[1]

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1. National Research Inst. for Metals, Tokyo (Japan)

Effects of [gamma] [leftrightarrow] [epsilon] cyclic transformations on the shape memory characteristics have been studied in an Fe-14Mn-6Si=9Cr-5Ni (wt.%) alloy. First, the effects of two cyclic transformations (one is the [gamma] to [epsilon] transformation by cooling and its reverse [epsilon] to [gamma] transformation by heating, and the other is the [gamma] to [epsilon] stress-induced transformation and its reverse transformation by heating) on the transformation temperatures were investigated by differential scanning calorimetry (DSC). M[sub s] and M[sub f] temperatures slightly decrease with increasing number of the [gamma] [leftrightarrow] [epsilon] ([epsilon] is formed on cooling) cyclic transformations. The effect of the [gamma] [leftrightarrow] [epsilon] cyclic transformation ([epsilon] is stress-induced) on the A[sub f] temperature is fairly large, and it is remarkably increased with increasing number of the [gamma] [leftrightarrow] [epsilon] cyclic transformations. The amount of martensite remarkably increases with increasing number of the [gamma] [leftrightarrow] [epsilon] cyclic transformations ([epsilon] is formed on cooling). Next, the effect of [gamma] [leftrightarrow] [epsilon] cyclic transformation ([gamma] to [epsilon] stress-induced transformation and its reverse transformation by heating under various stresses) on the recovery stress was investigated. When the [gamma] [leftrightarrow] [epsilon] transformation is repeated, the recovery stress first increases remarkably and then decreases monotonically irrespective of the stress applied during the reverse transformation. This increase of recovery stress is attributed to not only the increase of elongation when the specimen is deformed but also to the increase of stacking faults, which act as nucleation sites for martensite. The monotonic decrease of recovery stress is attributed to the decrease of elongation.

• OSTI ID: 7289458
• Journal Information: Materials Characterization; (United States), Journal Name: Materials Characterization; (United States) Vol. 32:3; ISSN 1044-5803; ISSN MACHEX
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102* -- Metals & Alloys-- Structure & Phase Studies
ALLOYS
CHROMIUM ALLOYS
IRON ALLOYS
IRON BASE ALLOYS
MANGANESE ALLOYS
MECHANICAL PROPERTIES
NICKEL ALLOYS
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
SILICON ALLOYS
THERMAL CYCLING
THERMODYNAMIC PROPERTIES
TRANSITION TEMPERATURE