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Title: Degradation of the shape memory effect in copper-base alloys

Abstract

The reversible transformation of the parent phase (austenite) to the product phase (martensite) is the basis of several shape memory properties in specific Cu-base alloys. In this respect, the two-way memory effect (TWME) refers the reversible, spontaneous shape change from a hot austenitic shape to a cold martensitic shape during cooling and heating without the application of external stresses. It is known that the magnitude of the TWME decrease during thermal or thermomechanical cycling, in particular in Cu-base shape memory alloys. It is however important to remark that this decrease, indicated as degradation of the TWME, can be caused as well by a decrease of the spontaneous martensitic strain, i.e. a degradation of the cold shape, as by an increase of the residual austenitic strain, i.e. a degradation of the hot shape, or by a combination of both. The degradation of the TWME, and of the hot and cold shape is influenced by a number of factors including the alloy composition, the processing, the heat treatment, the training procedure and the parameters of the thermal or thermomechanical cycling. The knowledge of the degradation phenomena is still limited. In a subsequent study of the relationships between training and the two-way memorymore » behavior, the authors have shown that the degradation of the hot shape already starts during training. It was found that the residual austenitic strain [gamma][sub a] increases gradually during training cycling; [gamma][sub a] is also in the case of training composed of a recoverable residual strain [gamma][sub ar] and a non-recoverable residual strain [gamma][sub anr]. The present paper reports the results of the specific experiments which were designed based upon the results described above. The evolutions during thermal cycling of the TWME, of the martensitic strain and austenitic strain, and of the recoverable and non-recoverable austenitic strain are presented and discussed.« less

Authors:
; ;  [1]
  1. Katholieke Univ. Leuven, Heverlee (Belgium). Dept. of Metallurgy and Materials Science
Publication Date:
OSTI Identifier:
6935631
Resource Type:
Journal Article
Journal Name:
Scripta Metallurgica et Materialia; (United States)
Additional Journal Information:
Journal Volume: 31:11; Journal ID: ISSN 0956-716X
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; COPPER BASE ALLOYS; SHAPE MEMORY EFFECT; CONTROL; CRYSTAL-PHASE TRANSFORMATIONS; THERMAL CYCLING; ALLOYS; COPPER ALLOYS; PHASE TRANSFORMATIONS; 360102* - Metals & Alloys- Structure & Phase Studies

Citation Formats

Stalmans, R, Van Humbeeck, J, and Delaey, L. Degradation of the shape memory effect in copper-base alloys. United States: N. p., 1994. Web. doi:10.1016/0956-716X(94)90076-0.
Stalmans, R, Van Humbeeck, J, & Delaey, L. Degradation of the shape memory effect in copper-base alloys. United States. https://doi.org/10.1016/0956-716X(94)90076-0
Stalmans, R, Van Humbeeck, J, and Delaey, L. Thu . "Degradation of the shape memory effect in copper-base alloys". United States. https://doi.org/10.1016/0956-716X(94)90076-0.
@article{osti_6935631,
title = {Degradation of the shape memory effect in copper-base alloys},
author = {Stalmans, R and Van Humbeeck, J and Delaey, L},
abstractNote = {The reversible transformation of the parent phase (austenite) to the product phase (martensite) is the basis of several shape memory properties in specific Cu-base alloys. In this respect, the two-way memory effect (TWME) refers the reversible, spontaneous shape change from a hot austenitic shape to a cold martensitic shape during cooling and heating without the application of external stresses. It is known that the magnitude of the TWME decrease during thermal or thermomechanical cycling, in particular in Cu-base shape memory alloys. It is however important to remark that this decrease, indicated as degradation of the TWME, can be caused as well by a decrease of the spontaneous martensitic strain, i.e. a degradation of the cold shape, as by an increase of the residual austenitic strain, i.e. a degradation of the hot shape, or by a combination of both. The degradation of the TWME, and of the hot and cold shape is influenced by a number of factors including the alloy composition, the processing, the heat treatment, the training procedure and the parameters of the thermal or thermomechanical cycling. The knowledge of the degradation phenomena is still limited. In a subsequent study of the relationships between training and the two-way memory behavior, the authors have shown that the degradation of the hot shape already starts during training. It was found that the residual austenitic strain [gamma][sub a] increases gradually during training cycling; [gamma][sub a] is also in the case of training composed of a recoverable residual strain [gamma][sub ar] and a non-recoverable residual strain [gamma][sub anr]. The present paper reports the results of the specific experiments which were designed based upon the results described above. The evolutions during thermal cycling of the TWME, of the martensitic strain and austenitic strain, and of the recoverable and non-recoverable austenitic strain are presented and discussed.},
doi = {10.1016/0956-716X(94)90076-0},
url = {https://www.osti.gov/biblio/6935631}, journal = {Scripta Metallurgica et Materialia; (United States)},
issn = {0956-716X},
number = ,
volume = 31:11,
place = {United States},
year = {1994},
month = {12}
}