Ultra-large single crystals by abnormal grain growth

Producing a single crystal is expensive because of low mass productivity. Therefore, many metallic materials are being used in polycrystalline form, even though material properties are superior in a single crystal. Here we show that an extraordinarily large Cu-Al-Mn single crystal can be obtained by...

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Bibliographic Details
Published in:	Nature communications Vol. 8; no. 1; pp. 354 - 9
Main Authors:	Kusama, Tomoe, Omori, Toshihiro, Saito, Takashi, Kise, Sumio, Tanaka, Toyonobu, Araki, Yoshikazu, Kainuma, Ryosuke
Format:	Journal Article
Language:	English
Published:	London Nature Publishing Group UK 25-08-2017 Nature Publishing Group Nature Portfolio
Subjects:	639/166/988 639/301/1023/1026 639/301/1023/303 Crystal growth Crystals Grain growth Heat treatments Humanities and Social Sciences multidisciplinary Science Science (multidisciplinary) Shape memory alloys Single crystals Superelasticity Thermal cycling
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Summary:	Producing a single crystal is expensive because of low mass productivity. Therefore, many metallic materials are being used in polycrystalline form, even though material properties are superior in a single crystal. Here we show that an extraordinarily large Cu-Al-Mn single crystal can be obtained by abnormal grain growth (AGG) induced by simple heat treatment with high mass productivity. In AGG, the sub-boundary energy introduced by cyclic heat treatment (CHT) is dominant in the driving pressure, and the grain boundary migration rate is accelerated by repeating the low-temperature CHT due to the increase of the sub-boundary energy. With such treatment, fabrication of single crystal bars 70 cm in length is achieved. This result ensures that the range of applications of shape memory alloys will spread beyond small-sized devices to large-scale components and may enable new applications of single crystals in other metallic and ceramics materials having similar microstructural features. Growing large single crystals cheaply and reliably for structural applications remains challenging. Here, the authors combine accelerated abnormal grain growth and cyclic heat treatments to grow a superelastic shape memory alloy single crystal to 70 cm.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	2041-1723 2041-1723
DOI:	10.1038/s41467-017-00383-0