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Author Schryvers, D.; Tirry, W.; Yang, Z.
Title Advanced TEM investigations on Ni-Ti shape memory material: strain and concentration gradients surrounding Ni4Ti3 precipitates Type P1 Proceeding
Year 2005 Publication Abbreviated Journal
Volume Issue Pages 329-338
Keywords P1 Proceeding; Electron microscopy for materials research (EMAT)
Abstract Lattice deformations and concentration gradients surrounding Ni4Ti3 precipitates grown by appropriate annealing in a Ni51Ti49 B2 austenite matrix are determined by a combination of TEM techniques. Quantitative Fourier analysis of HRTEM images reveals a deformed nanoscale region with lattice deformations up to 2% while EELS and EDX indicate a Ni depleted zone up to 150 nm away from the matrix-precipitate interface.
Address
Corporate Author Thesis
Publisher Place of Publication s.l. Editor
Language Wos (up) Publication Date 0000-00-00
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1-55899-790-3 ISBN Additional Links UA library record; WoS full record;
Impact Factor Times cited Open Access
Notes Approved Most recent IF: NA
Call Number UA @ lucian @ c:irua:55688 Serial 75
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Author Schryvers, D.; Tirry, W.; Yang, Z.
Title Ni4Ti3 precipitates and their influence on the surrounding NiTi matrix Type P1 Proceeding
Year 2005 Publication Abbreviated Journal
Volume Issue Pages 205-220
Keywords P1 Proceeding; Electron microscopy for materials research (EMAT)
Abstract The properties of the shape memory behaviour of Ni-rich binary NiTi are strongly dependant on the thermal history of the material. In this respect the changing of transformation temperatures of the underlying martensitic transformation and the occurrence of multiple step transformations are the most important phenomena. Part of the explanation is found in the presence of Ni4Ti3 precipitates in the B2 matrix after particular heat treatments. The formation of these precipitates changes the Ni concentration of the matrix and induces a strain field, with both of these aspects expected to be of importance. In this work atomic resolution and analytical TEM (transmission electron microscopy) techniques are used to obtain quantitative information concerning these two main features. Furthermore, the known structure of Ni4Ti3 is refined by a least squares optimization of quantitative electron diffraction data. The high-resolution TEM results show that there are strains up to 2% in the matrix surrounding the precipitates and they gradually increase until a maximum is reached when moving away from the interface. Analytical results reveal a global decrease of Ni content in the matrix when sufficient precipitates are present and a gradient in their close vicinity. The refinement of the structure shows atomic displacements, thereby increasing our understanding of the shrinking of the precipitate lattice with respect to the matrix.
Address
Corporate Author Thesis
Publisher Minerals, Metals Materials Society Place of Publication Warrendale Editor
Language Wos (up) Publication Date 0000-00-00
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN ISBN Additional Links UA library record; WoS full record;
Impact Factor Times cited Open Access
Notes Approved Most recent IF: NA
Call Number UA @ lucian @ c:irua:94759 Serial 3549
Permanent link to this record