Superlattice dislocations in Ti-rich polysynthetically twinned crystals of TiAl

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	Superlattice dislocations in Ti-rich polysynthetically twinned crystals of TiAl
	Y. Liu ; D. L. Lin ; Z. G. Liu ; Z. G. Wang
刊名	Philosophical Magazine a-Physics of Condensed Matter Structure Defects and Mechanical Properties
	1999
卷号	79 期号:12 页码:2965-2978
关键词	room-temperature deformation mechanisms yield stress lamellar structure single-crystals faulted dipoles pst crystals base alloys al dependence
ISSN号	0141-8610
中文摘要	The behaviour of superlattice dislocations in polysynthetically twinned (PST) TiAl crystals deformed from room temperature to 850 degrees C is studied by transmission electron microscopy. The dissociation modes undergo significant changes with increasing deformation temperature. At room temperature, the [011] superlattice dislocations dissociate into superpartials including either an antiphase boundary and a superlattice intrinsic stacking fault (SISF), or superlattice extrinsic stacking faults (SESFs), forming faulted dipoles, and are sessile. The 1/2[112] superlattice dislocations dissociate into faulted dipoles and are also sessile. While the dislocation configurations in the crystals deformed at 400 degrees C and 600 degrees C are identical with those in the crystals deformed at room temperature, one important variation is that the density of faulted dipoles decreases with increasing deformation temperature. In-situ heating observations show that self-annihilation of the SESF-bounding hairpin superpartial occurs within a temperature range that compares with that of the brittle-ductile transition of PST TiAl crystals. At 850 degrees C, most [011] superlattice dislocations dissociate to form Kear-Wilsdorf locks. The 1/2[112] superlattice dislocations are edge in character, dissociated into superpartials bordering a SISF and are glissile. The experimental observations suggest that the behaviour of 1/2[112] superlattice dislocations is an important factor controlling the mechanism of brittle-ductile transition of PST TiAl crystals.
原文出处	://WOS:000084280500007
公开日期	2012-04-14
内容类型	期刊论文
源URL	[http://ir.imr.ac.cn/handle/321006/37431]
专题	金属研究所_中国科学院金属研究所
推荐引用方式 GB/T 7714	Y. Liu,D. L. Lin,Z. G. Liu,et al. Superlattice dislocations in Ti-rich polysynthetically twinned crystals of TiAl[J]. Philosophical Magazine a-Physics of Condensed Matter Structure Defects and Mechanical Properties,1999,79(12):2965-2978.
APA	Y. Liu,D. L. Lin,Z. G. Liu,&Z. G. Wang.(1999).Superlattice dislocations in Ti-rich polysynthetically twinned crystals of TiAl.Philosophical Magazine a-Physics of Condensed Matter Structure Defects and Mechanical Properties,79(12),2965-2978.
MLA	Y. Liu,et al."Superlattice dislocations in Ti-rich polysynthetically twinned crystals of TiAl".Philosophical Magazine a-Physics of Condensed Matter Structure Defects and Mechanical Properties 79.12(1999):2965-2978.