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Title: The two way memory effect in TiNi alloys

Abstract

The two way memory effect (TWME) in shape memory alloys represents a reversible spontaneous shape changes during cooling and heating processes. This is a consequence of reversible phase transformations observed without application of any external stresses. The TWME is usually obtained after a thermomechanical treatment often called training. The different opinions were published concerning the influence of R-phase formation in TiNi based alloys on the stability of TWME. Stachowiak and McCormick have stated that the formation of R-phase diminishes the extent of obtained reversible strain as well as the stability of TWME. In contrast to this conclusion, the authors observed enhanced stability of TWME in the cases when the R-phase formation precedes the martensitic transformation B2 {yields} B19{prime}. Repeating the heating cycles at loading of the memory materials, the complex degradation mechanisms of TiNi alloys occurs. The dislocation generation in the matrix of TiNi alloys (work hardening) strongly influences the maximum level of generated stresses and the extent of reversible strain. As a contribution to the explanation of physical principles of TWME, the present paper is devoted to the study of substructure after so called hard training at which the specimens are deformed ({var_epsilon} = 4%) and cyclically heated andmore » cooled down at constrained conditions.« less

Authors:
;  [1]
  1. Technical Univ. of Ostrava (Czech Republic). Inst. of Materials Engineering
Publication Date:
OSTI Identifier:
271581
Resource Type:
Journal Article
Journal Name:
Scripta Materialia
Additional Journal Information:
Journal Volume: 35; Journal Issue: 3; Other Information: PBD: 1 Aug 1996
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; TITANIUM ALLOYS; PHASE TRANSFORMATIONS; SHAPE MEMORY EFFECT; MICROSTRUCTURE; NICKEL ALLOYS; INTERMETALLIC COMPOUNDS; WIRES; COLD WORKING; DRAWING; ANNEALING; THERMOMECHANICAL TREATMENTS; TRANSITION TEMPERATURE; MARTENSITE; AUSTENITE; TRIGONAL LATTICES; TRANSMISSION ELECTRON MICROSCOPY; DISLOCATIONS

Citation Formats

Filip, P, and Mazanec, K. The two way memory effect in TiNi alloys. United States: N. p., 1996. Web. doi:10.1016/1359-6462(96)00162-5.
Filip, P, & Mazanec, K. The two way memory effect in TiNi alloys. United States. https://doi.org/10.1016/1359-6462(96)00162-5
Filip, P, and Mazanec, K. Thu . "The two way memory effect in TiNi alloys". United States. https://doi.org/10.1016/1359-6462(96)00162-5.
@article{osti_271581,
title = {The two way memory effect in TiNi alloys},
author = {Filip, P and Mazanec, K},
abstractNote = {The two way memory effect (TWME) in shape memory alloys represents a reversible spontaneous shape changes during cooling and heating processes. This is a consequence of reversible phase transformations observed without application of any external stresses. The TWME is usually obtained after a thermomechanical treatment often called training. The different opinions were published concerning the influence of R-phase formation in TiNi based alloys on the stability of TWME. Stachowiak and McCormick have stated that the formation of R-phase diminishes the extent of obtained reversible strain as well as the stability of TWME. In contrast to this conclusion, the authors observed enhanced stability of TWME in the cases when the R-phase formation precedes the martensitic transformation B2 {yields} B19{prime}. Repeating the heating cycles at loading of the memory materials, the complex degradation mechanisms of TiNi alloys occurs. The dislocation generation in the matrix of TiNi alloys (work hardening) strongly influences the maximum level of generated stresses and the extent of reversible strain. As a contribution to the explanation of physical principles of TWME, the present paper is devoted to the study of substructure after so called hard training at which the specimens are deformed ({var_epsilon} = 4%) and cyclically heated and cooled down at constrained conditions.},
doi = {10.1016/1359-6462(96)00162-5},
url = {https://www.osti.gov/biblio/271581}, journal = {Scripta Materialia},
number = 3,
volume = 35,
place = {United States},
year = {1996},
month = {8}
}