Acta Metallurgica

The substructure generated within the matrix by a migrating grain boundary has been investigated by etch pitting and transmission electron microscopy in an InP bicrystal and InAs polycrystals having an initial dislocation density of 103cm−2. It is shown that in the volume swept by a boundary, the dislocation density increases by a factor of ~104. Furthermore, this increase is observed to depend upon the migration rate. Arguments based on growth accidents occurring during the boundary migration have been invoked to rationalize these observations which may be significant for the understanding of the residual dislocation content of crystalline materials after recrystallization, grain growth and phase transformations involving the motion of incoherent interfaces. Nous avons étudié par figures d'attaque et microscopie électronique en transmission la sousstructure produite dans la matrice par la migration d'un joint de grains, dans un bicristal d'InP et dans des polycristaux de InAs ayant une densité initiale de dislocations de 103cm−2. Nous montrons que la densité de dislocations est multipliée par un facteur de l'ordre de 104 dans le volume balayé par un joint de grains. De plus, cet accroissement dépend de la vitesse de migration. Des arguments reposant sur des accidents de croissance se produisant au cours de la migration du joint ont été invoqués pour comprendre ces observations; ils pourrraient être importants pour la compréhension de k teneur résiduelle en dislocations des matériaux cristallins apres la recristallisation, la croissance des grains et les transformations de phases mettant en jeu la migration d'interfaces incohérents. Die in der Matrix durch eine wandernde Korngrenze erzeugte Substruktur wurde an einem InP-Bikristall und an InAs-Polykristallen (Ausgangsversetzungsdichte 103cm−2) mittels Atzgrübchen und Durchstrahlungselektronenmikroskopie untersucht. In dem von einer Korngrenze durchquerten Volumen steigt die Versetzungsdichte um einen Faktor von ~ 104 an. Auβerdem hängt dieser Anstieg von der Wanderungsgeschwindigkeit ab. Argumente, die auf Wachstumseinflüssen während der Korngrenzwanderung betrachten, werden benutzt, diese Beobachtungen zu erklären. Diese: Beobachtungen können wichtig sein für das Verständnis der Versetzungsdichte, die in kristallinen Substanzen nach Rekristallisation, Kornwachstum und Phasenumwandlungen, die mit der Bewegung inkohärenter Grenzflächen einhergehen, übrig bleibt.

H. Gleiter

S. Mahajan

K.J. Bachmann

The generation of lattice dislocations by migrating boundaries

迁移界面对晶格位错生成的贡献

Brittle solids can be toughened by incorporating ductile inclusions into them. The inclusions bridge the crack and are stretched as the crack opens, absorbing energy which contributes to the toughness. To calculate the contribution to the toughness it is necessary to know the force-displacement curve for an inclusion, constrained (as it is) by the stiff, brittle matrix. Measured force-displacement curves for highly constrained metal wires are described and related to the unconstrained properties of the wire. The constraint was achieved by bonding the wire into a thick-walled glass capillary, which was then cracked in a plane normal to the axis of the wire and tested in tension. Constraint factors as high as 6 were found, but a lesser constraint gives a larger contribution to the toughness. The diameter of the wires (or of the inclusions) plays an important role. Simple, approximate, models for the failure of the wires are developed. The results allow the contribution of ductile particles to the toughness of a brittle matrix composite to be calculated. Il est possible de curcir des matériaux fragiles en leur incorporant des inclusions ductiles. Les inclusions traversent la fissure et s'allongent lorsque la fissure s'ouvre, absorbant de l'énergie qui contribue à la resilience. Pour calculer la contribution à la resilience, il est nécessaire de connaître la courbe force-déplacement d'une inclusion quand elle est contrainte par la matrice fragile et rigide. Nous décrivons les courbes expérimentales force-déplacement de fils métalliques fortement contraints, et nous les relions aux propriétés du fil non contraint. La contrainte est créée en fixant le fil à l'intérieur d'un capillaire en verre à parois épaisses, que l'on écrase ensuite dans un plan perpendiculaire à l'axe du fil, et que l'on déforme en traction. Les facteurs de contrainte peuvent atteindre 6, mais une contrainte moins élevée participe davantage à la resilience. Le diamètre des fils (ou celui des inclusions) joue un rôle important. Nous développons des modèles approchés simples de la rupture des fils. Les résultats permettent de calculer la contribution des particules ductiles à la resilience d'un composite à matrice fragile. Spröde Festkörper können mit eingebrachten duktilen Einschlüssen gehärtet werden. Wenn sich der Riβ öffnet, überbrücken die Einschlüsse den Riβ, sie werden gedehnt und absorbieren Energie und tragen so zur Festigkeitserhöhung bei. Um dessen Höhe zu berechnen, muβ man die Kraft-Weg-Kurve für einen Einschluβ, eingeengt durch die steife und spröde Matrix, kennen. Die an entsprechenden Metalldrähten gemessenen Kraft-Weg-Kurven werden beschrieben und mit Messungen des Verhaltens freier Drähte verglichen. Die Einschrämkung wurde dadurch erzeugt, daβ der Draht in dickwandige Glaskapillaren eingebettet wurde; diese wurden dann in einer Ebene senkrecht zur Drahtachse gebrochen und im Zugversuch verformt. Es ergeben sich Einschränkungsfaktoren bis zu 6; allerdings tragen geringere Faktoren stärker zur Zähigkeit bei. Der Durchmesser der Drähte (oder der Einschlüsse) ist sehr wichtig. Es werden einfache angenäherte Modelle für den Bruch der Drähte entwickelt. Die Ergebnisse ermöglichen, den Beitrag der duktilen Einschlüsse zur Zähigkeit einer spröden Matrix zu berechnen.

M.F. Ashby

F.J. Blunt

M. Bannister

Flow characteristics of highly constrained metal wires

高约束金属丝的流动特性

High-grade non-oriented electrical steel was successfully processed by controlling texture using strip casting technology. Remarkable abnormal grain growth of {100} grains occurred in the as-cast strip after isothermal annealing. This phenomenon is considered to be the synergistic effect involving the size advantage of coarse columnar grains and surface energy, where the normal grain growth was inhibited by thermal grooving in the surface layer. Special rotation path was identified during the cold rolling process and metastable {118} 〈110〉–{113} 〈110〉 texture dominated the deformation texture. The final annealed sheet exhibited strong Cube texture together with significantly superior magnetic properties.

J.L. Walter

A mechanism for secondary recrystallization in high-purity silicon iron

高纯硅铁中二次再结晶的机理

Abstract A growth equation for individual grains in single-phase materials is suggested. It is used to calculate a rate equation for normal grain growth and the size distribution in the material. It predicts a maximum size of twice the average size. The theory is modified to take into account the effect of second-phase particles. In an alternative treatment the array of grains is described in terms of a kind of defects introduced into a perfect array. The defects move through the array during grain growth. The rate of grain growth is calculated from the number of defects and their mobility. The defect concentration is predicted by comparing the two treatments. The defect-model predicts two grain size limits due to second-phase particles. Normal grain growth takes place below the lower limit. Abnormal grain growth can take place between the two limits if the material contains at least one very large grain. No grain growth can take place above the higher limit. Several possible mechanisms for the development of abnormal grain growth are examined. An explanation is offered for the observation that most of the well-known cases occur as the second-phase is dissolving.

M Hillert

On the theory of normal and abnormal grain growth

正常与异常晶粒生长理论

The structural changes occurring during the tempering of a 12%Cr-6%Mo-10%Co-0.1 %C steel have been investigated. It has been shown that an intermetallic compound R-phase is responsible for the marked secondary hardening but that the carbides M2X and M6C are also precipitated. The R-phase contained iron, chromium and molybdenum but little or no cobalt. By determining the orientation relationship between R-phase and ferrite it has been shown that the precipitation of R-phase in ferrite is theoretically favourable. Les variations de structure se produisant au cours du revenu d'un acier 12%Cr-6%Mo-10%Co-0,1 %C ont été étudiées. Les auteurs montrent qu'une phase constituée par un composé intermétallique R est responsable du durcissement secondaire prononcé, mais que les carbures M2X et M6C précipitent également. La phase R contient du fer, du chrome et du molybdène mais peu ou pas de cobalt. En déterminant la relation d'orientation entre la phase R et la ferrite, les auteurs montrent que la précipitation de la phase R dans la ferrite est favorisée par la théorie. Die während des Temperns von 12%Cr-6%Mo-10%Co-0,1 %C-Stahl auftretenden Strukturänderungen wurden untersucht. Es wurde gezeight, daβ eine R-Phase einer zwischenmetallischen Verbindung für die ausgeprägte sekundäre Verfestigung verantwortlich ist; jedoch scheiden sich auch M2X- und M6C-Karbide aus. Die R-phase enthält Eisen, Chrom und Molybdän, jedoch wenig oder gar kein Kobalt. Durch Bestimmung der Orientierungsbeziehung zwischen R-phase und Ferrit wird gezeigt, daβ die Ausscheidung der R-phase in Ferrit theoretisch günstig ist.

D.J Dyson

S.R Keown

A study of precipitation in a 12 %Cr-Co-Mo steel

12%Cr-Co-Mo钢中沉淀的研究

I Samajdar

B Verlinden

Leo Kestens

P Van Houtte

Physical Parameters Related to the Developments of Recrystallization Textures in an Ultra-Low Carbon Steel.

超低碳钢再结晶织构发展相关的物理参数。

Developments in deformation and recrystallization textures were studied in cold-rolled (50--90% reduction) ultra low carbon (ULC) steel using X-ray texture measurements and orientation imaging microscopy (OIM). During deformation, {gamma}-fiber (ND//{l_angle}111{r_angle}) increased between 0 and 50% reduction but then did not change significantly, while {alpha}-fiber (RD//{l_angle}110{r_angle}) increased progressively from 0 to 90% reduction. After complete recrystallization, however, a steady increase in {gamma} and almost no changes in {alpha} were observed with increasing strain. Developments in recrystallization textures were attributed to two parameters: (1) spacings ({lambda}{sub i}, as measured along the normal direction, ND, where i can be a specific component of {alpha}/{gamma}-fibers) of the {alpha}/{gamma} deformed bands; and (2) their relative ability to form recrystallized grains. While {lambda}{sub i} was determined by the deformation texture and the thicknesses of the deformed grains/bands and naturally decreased with increasing strain, estimations of parameter (2) were obtained from the so-called nucleation factors (N{sub i}, defined as the number of recrystallized i grains per i band--as measured/estimated along the ND). At higher strains, noticeable drops in the N{sub i}s of {alpha}-fiber were observed. Two plausible causes for such drops were increased stored energy advantages for {gamma} bands and orientation pinning in some of the {alpha}more » regions.« less

超低碳钢中再结晶织构发展的相关物理参数。

出版信息	出版商: University of Toronto Press，出版周期: ，期刊类型: journal，开源期刊: 否
基本数据	创刊年份: 1957，原创研究文献占比: ，自引率:， Gold OA占比:

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The generation of lattice dislocations by migrating boundaries

Flow characteristics of highly constrained metal wires

A mechanism for secondary recrystallization in high-purity silicon iron

On the theory of normal and abnormal grain growth

A study of precipitation in a 12 %Cr-Co-Mo steel

Physical Parameters Related to the Developments of Recrystallization Textures in an Ultra-Low Carbon Steel.

Physical Parameters Related to the Developments of Recrystallization Textures in an Ultra-Low Carbon Steel.

Physical Parameters Related to the Developments of Recrystallization Textures in an Ultra-Low Carbon Steel.

Physical Parameters Related to the Developments of Recrystallization Textures in an Ultra-Low Carbon Steel.

Physical Parameters Related to the Developments of Recrystallization Textures in an Ultra-Low Carbon Steel.