Structure of twin boundaries in L12ordered alloys

Tichelaar, F.D.; Schapink, F.W.

doi:10.1080/01418618608242891

Cited by 23 publications

(8 citation statements)

References 6 publications

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“…The broad twin plane are determined by means of transmission electron microscope to be {111} plane as shown in Fig. 6, in agreement with those reported by many investigators in Ni 3 Al-based alloys 15,32) and Cu 3 Au; 20) thus the ledges on twin plane correspond to incoherent twin planes.…”

Section: Annealing Twins In Binary Ni-al Alloysupporting

confidence: 76%

Annealing Twinning in Boron-Doped Ni3Al

Wei

Mishima

2002

Mater. Trans.

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Dependence of frequency of annealing twinning events on annealing temperature and composition, especially boron content, in polycrystalline Ni 3 Al alloys has been investigated by means of optical and transmission electron microscopy, and also by evaluation of coherent twin boundary energy via counting the wrong atomic bonds across twin boundaries. Microstructural observation found that after homogenization at temperatures from 1000 to 1360 • C both binary and boron-doped Ni 3 Al alloys without prestrain show annealing twins only on the Al-rich side with respect to stoichiometry below 1200 • C. Above 1200 • C annealing twinning may also take place on the Ni-rich side of stoichiometry in the binary alloy system but no twins were found in the γ + γ two-phase field. In contrast to plenty of annealing twins in binary alloys, addition of boron decreases greatly the number of twins. 0.2 at% addition significantly decreases the frequency of twinning events and no twins appear above 1200 • C. 0.5 at% boron almost cleans out all the twins from the microstructure. Annealing twinning is supposed to be completed by two processes including sweeping of 1/3 211 superpartial dislocations on successive (111) planes and simultaneous diffusion of boron atoms into the energetically favorable octahedral interstice that are surrounded by six Ni atoms. Boron acts as a strong obstacle to the movement of the superpartial dislocations and greatly increases difficulty in annealing twinning.

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Section: Annealing Twins In Binary Ni-al Alloysupporting

confidence: 76%

Annealing Twinning in Boron-Doped Ni3Al

Wei

Mishima

2002

Mater. Trans.

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“…Discs (3 mm diameter) were punched out of the sheets and electrochemically thinned in a solution containing 10% perchloric acid and 90% acetic acid (Tenupol 3 at 140C under 8 V at a slow rate [11]). Electropolishing induces the surface deposition of gold aggregates.…”

Section: Sample Preparationmentioning

confidence: 99%

High-resolution electron microscopy studies of antiphase boundaries in Cu3Au

Potez

Loiseau

1994

Interface Sci

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We report the results of a crystallographic analysis of antiphase boundaries (APB) in Cu3Au obtained by using high-resolution electron microscopy. Our observations corroborate the conclusions of previous work, based on conventional electron microscopy, which indicate that antiphase boundaries are mainly located in the cube planes. We found that the deviation of the average APB orientation from the cube planes is related to the formation of kinks on an atomic scale. Moreover, the identification of the boundary plane shows that the APBs are mostly conservative. These results are discussed and interpreted in the framework of a pairwise potential approach with predominant nearest neighbor interactions.

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“…In both materials however, sublattices in adjacent crystals can be occupied in different ways which affects the boundary structure. In ordered CuaAu, two different structures of a CTB exist, a symmetrical structure (S-structure) or an asymmetrical structure (A-structure), which can, for example, be separated by an APB terminating at the boundary [21]. In NizAI only the S structure is expected, since it has a much lower energy than the A-structure [22] which is related to the high APB energy in NizAI.…”

Section: Ctb Structure and The Interaction Of Dislocations With Ctbsmentioning

confidence: 99%

“…In NizAI only the S structure is expected, since it has a much lower energy than the A-structure [22] which is related to the high APB energy in NizAI. Detailed information on CTB structures in L12-ordered alloys can be found in [21][22][23][24].…”

Section: Ctb Structure and The Interaction Of Dislocations With Ctbsmentioning

confidence: 99%

Slip transfer at coherent twin boundaries in Ni3Al and ordered Cu3Au

et al. 1994

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Slip transfer at coherent twin boundaries in L12-ordered alloys has been investigated by analysis of plastically deformed Cu3Au and Ni3A1 specimens in a transmission electron microscope. A comparison between the ex situ deformed material and previous in situ experiments is made. In ordered Cu3Au, antiphase boundaries induced by slip transfer have been found at a coherent twin boundary (CTB), similar to the in situ deformed material. On the other hand, in Ni3AI superlattice intrinsic stacking faults (SISFs) were detected at CTBs which have not been observed in in situ deformed material. A possible mechanism for SISF formation is discussed. The transfer of slip, and the associated creation of stacking faults at CTBs in both materials is described in terms of absorption of superdislocations in the boundary and the general criteria for slip transfer at grain boundaries.

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Structure of twin boundaries in L1₂ordered alloys

Cited by 23 publications

References 6 publications

Annealing Twinning in Boron-Doped Ni<SUB>3</SUB>Al

Annealing Twinning in Boron-Doped Ni<SUB>3</SUB>Al

High-resolution electron microscopy studies of antiphase boundaries in Cu3Au

Slip transfer at coherent twin boundaries in Ni3Al and ordered Cu3Au

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