Interphase boundary structures of intragranular proeutectoid α plates in a hypoeutectoid TiCr alloy

Furuhara, Tadashi; Howe, James M.; Aaronson, H.I.

doi:10.1016/0956-7151(91)90104-9

Cited by 170 publications

(108 citation statements)

References 35 publications

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“…[196] The transformation strain itself is an invariant plane strain, with the invariant plane parallel to the shear plane 1 " 100 À Á a . This formation mechanism is similar to that proposed for c¢ plates in Mg-Gd-Zn [203] and Mg-Y-Zn [214] alloys, proeutectoid a plates in a TiCr alloy, [262][263][264] and for precipitate plates of c¢ in Al-Ag alloys, h¢ in Al-Cu alloys, T 1 in Al-Cu-Li(-Mg-Ag) alloys, and X in Al-Cu-Mg-Ag alloys. [265,266] Figure 36 shows schematically an initial b 1 platelet that has a thickness of one unit cell and is constrained within the a-Mg matrix phase.…”

Section: Microstructural Design For Higher Strengthmentioning

confidence: 55%

Precipitation and Hardening in Magnesium Alloys

Nie

2012

Metall Mater Trans A

1,351

519

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Magnesium alloys have received an increasing interest in the past 12 years for potential applications in the automotive, aircraft, aerospace, and electronic industries. Many of these alloys are strong because of solid-state precipitates that are produced by an age-hardening process. Although some strength improvements of existing magnesium alloys have been made and some novel alloys with improved strength have been developed, the strength level that has been achieved so far is still substantially lower than that obtained in counterpart aluminum alloys. Further improvements in the alloy strength require a better understanding of the structure, morphology, orientation of precipitates, effects of precipitate morphology, and orientation on the strengthening and microstructural factors that are important in controlling the nucleation and growth of these precipitates. In this review, precipitation in most precipitation-hardenable magnesium alloys is reviewed, and its relationship with strengthening is examined. It is demonstrated that the precipitation phenomena in these alloys, especially in the very early stage of the precipitation process, are still far from being well understood, and many fundamental issues remain unsolved even after some extensive and concerted efforts made in the past 12 years. The challenges associated with precipitation hardening and age hardening are identified and discussed, and guidelines are outlined for the rational design and development of higher strength, and ultimately ultrahigh strength, magnesium alloys via precipitation hardening.

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Section: Microstructural Design For Higher Strengthmentioning

confidence: 55%

Precipitation and Hardening in Magnesium Alloys

Nie

2012

Metall Mater Trans A

1,351

519

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“…Кроме того, на торцевой грани наблюдали дислокации несоответствия "a" [11,12] и "a + c"-типа [19]. [26].…”

Section: A) все эти плоскости содержат направле-ние [0001] α || [110]unclassified

“…1b). Результаты моделирования [11] и вы-сокоразрешающей электронной микроскопии по-казали [12,13,20,21], что кроме дислокаций несо-ответствия на широкой поверхности сопряжения α и β пластин формируются структурные ступеньки. Присутствие структурных ступенек, террасы кото-рых образованы плоскостями (011 − 0) α || (11 − 2) β , хоро-шо объясняет выполнение ОС Бюргерса при больших индексах Миллера «макроскопической плоскости» габитуса (рис.…”

Section: Introductionunclassified

“…Строение торцевой β / α границы вызывает наиболь-шие дискуссии [11,12,19]. Вероятно, это связано с тем, что торцевая поверхность раздела может состоять из фа-сеток, образованных разными парами плоскостей.…”

Section: Introductionunclassified

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Effect of temperature on the specific energy of β / α interfaces in Ti-6Al-4V alloy

Murzinova¹

2017

LoM

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Most of titanium alloys contain two phases at temperatures of processing and exploitation: α-phase with HCP lattice and β-phase with BCC lattice. Stability of two-phase structure and thermodynamics of β / α transformation, which occurs in a wide range of temperatures, considerably depend on the specific energy of interphase boundaries, and, consequently, on their structure. Basing on the literature data, four schemes of "planar" semicoherent interfaces, in which mismatches in interatomic distances are accommodated by two or three sets of edge misfit dislocations, were plotted. Such types of conjugation are observed on side and end interfaces of lamellas in titanium alloys. The procedure developed by J. H. van der Merwe and G. J. Shiflet was used for estimation of specific energy of interphase boundaries in Ti-6Al-4V alloy. Effect of temperature and content of alloying elements on lattice parameters and elastic properties of the α-and β-phases in Ti-6Al-4V alloy was taken into account for calculations. This approach allowed one to estimate the change in the energy of interphase boundaries in the alloy in temperature interval 600 -975°C, where diffusion β / α transformation and enrichment of β-phase by vanadium are observed. It was shown that the energy of interphase boundaries in Ti-6Al-4V alloy decreased by 1.3 -1.5 times with increasing temperature from 600 to 975°C at all examined types of conjugation. Depending on the structure the energy of interphase boundaries can vary from 0.201 to 0.337 J / m 2 at 975°C and from 0.298 to 0.429 J / m 2 at 600°C. Во многих титановых сплавах при температурах обработки и эксплуатации присутствуют две фазы: α-фаза с ГПУ решеткой и β-фаза с ОЦК решеткой. Стабильность двухфазной структуры и термодинамика фазового β / α превра-щения, которое протекает в широком интервале температур, во многом зависят от удельной энергии межфазных границ, и, следовательно, их строения. На основе обобщения литературных данных об атомном и дислокационном строении границ между фазами с ОЦК и ГПУ решетками предложены четыре схемы строения «плоских» полукоге-рентных межфазных границ, на которых несоответствия межатомных расстояний компенсируются двумя или тремя рядами краевых дислокаций несоответствия. Границы сопряжения такого типа наблюдаются на боковых и торцевых гранях пластин в титановых сплавах. По методике, разработанной ван дер Мерве и Шифлитом, выполнена оценка удельной энергии межфазных границ разного типа в сплаве Ti-6Al-4V. Расчеты проводились с учетом литературных данных о влиянии содержания легирующих элементов и температуры на параметры решеток и упругие свойства фаз сплава Ti-6Al-4V. Это позволило оценить изменение энергии межфазных границ в сплаве Ti-6Al-4V в интер-вале температур 600 -975°С, при которых наблюдается развитие диффузионного β / α превращения и интенсивное обогащение β-фазы ванадием. Показано, что при всех вариантах сопряжения энергия межфазных границ в сплаве Ti-6Al-4V монотонно уменьшается в 1,3 -1,5 раза с повышением температуры от 600 до 975°С. При постоянной тем-пер...

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“…The habit plane in some systems, in particular between metal matrix and metal oxide, carbide or nitride [2][3][4][5] parallels a lowindices crystallographic plane in one or both lattices adjoining the interface whereas the habit plane in other systems cannot be simply expressed by any low-indices planes in either lattice and hence it is usually termed irrational habit plane. The irrational habit planes are commonly observed in a precipitation system, such as {5 3 3} Cu habit plane between Cr-rich precipitates and Cu matrix [6], {11, 11, 13}  habit plane between proeutectoid  phase and  matrix in a Ti-Cr alloy [7], {3.0, 2.2, 3.4}  habit plane between proeutectoid  phase and  phase in a Zr-Nb alloy [8], and {1 1 4}  habit plane between proeutectoid cementite and austenite in a hypereutectoid steel [9]. The irrational habit planes are also reproducibly observed in many martensitic transformations, including the wellknown {2 2 5}  , {2 5 9}  and {5 5 7}  habit plane in ferrous alloys [10,11] and {3 3 4}  habit plane in Ti alloys [12].…”

Section: Accepted Manuscriptmentioning

confidence: 99%

A simple and inclusive method to determine the habit plane in transmission electron microscope based on accurate measurement of foil thickness

Qiu

Zhang

2014

Materials Characterization

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A simple and inclusive method is proposed for accurate determination of the habit plane between bicrystals in Transmission Electron Microscope. Whilst this method can be regarded as a variant of surface trace analysis, the major innovation lies in the improved accuracy and efficiency of foil thickness measurement, which involves a simple tilt of the thin foil about a permanent tilting axis of the specimen holder, rather than cumbersome tilt about the surface trace of the habit plane.Experimental study has been done to validate this proposed method in determining the habit plane between lamellar  2 plates and  matrix in a Ti-Al-Nb alloy. Both high accuracy (1) and high precision (1) have been achieved by using the new method. The source of the experimental errors as well as the applicability of this method is discussed. Some tips to minimise the experimental errors are also suggested.

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Interphase boundary structures of intragranular proeutectoid α plates in a hypoeutectoid TiCr alloy

Cited by 170 publications

References 35 publications

Precipitation and Hardening in Magnesium Alloys

Precipitation and Hardening in Magnesium Alloys

Effect of temperature on the specific energy of β / α interfaces in Ti-6Al-4V alloy

A simple and inclusive method to determine the habit plane in transmission electron microscope based on accurate measurement of foil thickness

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