scispace - formally typeset
Search or ask a question

Showing papers on "Equiaxed crystals published in 1973"


Journal ArticleDOI
TL;DR: In this article, the dislocation substructure generated during compressive creep of MgO single crystals was investigated using both etchpit and transmission electron microscopy techniques, and the type of dislocations substructure is dependent on strain.
Abstract: The dislocation substructure generated during compressive creep of MgO single crystals has been investigated using both etch-pit and transmission electron microscopy techniques. The type of dislocation substructure is dependent on strain. During transient creep nearly parallel cell walls are found whereas in steady state creep a nearly equiaxed network of cells is built up. Measurements of the density ρ of dislocations not associated with cell walls and of the cell wall area per volume S v reveal the following trends: During primary creep both ρ and S v are functions of strain; ρ decreases while S v increases with increasing strain. During steady state creep ρ and S v are constant. The isothermal stress dependence of the steady state values of ρ and S v can be described by relations ρ ∼ σ1·4, and SV∼σ0·7.

65 citations


Journal ArticleDOI
TL;DR: Stress-strain curves have been obtained for a superplastically deformed industrial 60/40 brass tested in tension under constant true strain-rate conditions at 600 ˚C as discussed by the authors.
Abstract: Stress-strain curves have been obtained for a superplastically deformed industrial 60/40 brass tested in tension under constant true strain-rate conditions at 600‡C. This alloy produced by extrusion shows a fibrous structure with elongated grains. It is shown that the flow stress is influenced by two microstructural factors, i.e. the change of phase shape which becomes approximately equiaxed and the variation of the phase size during superplastic deformation. These factors are of different relative importance according to the strain-rate.

55 citations


Journal ArticleDOI
TL;DR: In this article, the deformation behavior of three different neutron irradiated copper alloys has been investigated using mainly transmission electron microscopy, and the results are compared with those for deformed irradiated ionized copper crystals and unirradiated alloys.

41 citations


Journal ArticleDOI
TL;DR: In this article, it has been observed that the high temperature B 2 structure decomposes eutectoidally into two intermetallic compounds Ti 2 Ni (f.c.) and Ni 3 Ti (h.c.p.) at 650 ± 10°C.

33 citations


Journal ArticleDOI
01 Jan 1973
TL;DR: In this paper, microsegregation measurements and calculations were carried out for solidification of small melts of Cu-40 wt pct Ni under conditions in which both the cooling rate and the local rate of heat extraction during dendrite growth were varied.
Abstract: Microsegregation measurements and calculations were carried out for solidification of small melts of Cu-40 wt pct Ni under conditions in which both the cooling rate and the local rate of heat extraction during dendrite growth were varied. These demonstrated that the supercooling required to support dendrite growth significantly reduces the microsegregation in the completely frozen ingot. The importance of this for the different microsegregation in columnar and equiaxed regions of large ingots is briefly discussed.

26 citations


Journal ArticleDOI
TL;DR: In this article, the microstructural variation observed within the same or different foils was attributed to the large number of combinations of processing variables the most important of which are: dropping temperature, platen velocity and platen surface conditions.

25 citations


Journal ArticleDOI
TL;DR: The microstructure of foils obtained by splat-cooling superheated droplets in the liquid-solid range was duplex with coarse dendrite cells embedded in a fine rod-like dendritic structure as mentioned in this paper.

13 citations


Journal ArticleDOI
Sidney Diamond1
TL;DR: The morphology of the particles of aluminosalicylate complex precipitated from salicylic acid solution by tricalcium aluminate (C3A) was examined by scanning electron microscopy as discussed by the authors.
Abstract: The morphology of the particles of aluminosalicylate complex precipitated from salicylic acid solution by tricalcium aluminate (C3A) was examined by scanning electron microscopy. Agglomerations of small (0.3 μm) equiaxed particles are precipitated from concentrated solutions and are accompanied by peculiar hexagonal prismatic “crystallites” with rounded ends thought to be Ca(OH)2. In more dilute solutions distorted hexagonal plates of C4AH13-type compounds are also formed.

12 citations


Patent
Bolling G1, Cole G1
01 Feb 1973
TL;DR: In this article, a method of controlling the grain or solidification structure in castings which have been prepared from inoculated metals is presented, where the inoculated molten metal is subjected to inertial effects during solidification comprised of oscillation and steady state rotation.
Abstract: This invention teaches a method of controlling the grain or solidification structure in castings which have been prepared from inoculated metals. The inoculated molten metal is subjected to inertial effects during solidification comprised of oscillation and steady state rotation. The invention makes it possible to selectively produce in such castings predetermined zones of equiaxed or columnar grain structures.

3 citations


Book ChapterDOI
01 Jan 1973
TL;DR: In the first years of industrial production of semis of titanium alloys, hot working was carried out in a way to achieve a fine grained microstructure with equiaxed alpha and intergranular beta as mentioned in this paper.
Abstract: During the first years of industrial production of semis of titanium alloys, hot working was carried out in a way to achieve a fine grained microstructure with equiaxed alpha and intergranular beta (1). Heating and heat treating in the beta field was believed to be detrimental to the quality of the products because of the grain growth. A reduction by hot working of 80 % at 950°C or of 30 to 50 % at 900°C was considered necessary to obtain the desired grain refinement of the Ti 6A1 4V-alloy (2).

1 citations


Journal ArticleDOI
TL;DR: In this article, a study of the structure of austenite after HTTMT with 70 and 50% deformation by rolling showed that the beginning of recrystallization depends on the deformation temperature and the time interval after rolling of steels.
Abstract: 1. Studies of the structure of austenite after HTTMT with 70 and 50% deformation by rolling showed that the beginning of recrystallization depends on the deformation temperature and the time interval after rolling of steels 18Kh5N2MVFSB, 34Kh5N2MVFSB, and 56Kh5N2MVFSB. Recrystallization of austenite at the stage of replacement of the deformed grains with equiaxed grains in the steel with 0.18% C after 70% deformation begins in less than 5 sec at 1050°, after 5 sec at 980°, and after 10 min at 880°. Lowering the deformation to 50% at 980° slows down the beginning of this stage (120 sec), while an increase of the carbon content accelerates recrystallization from 120–300 to 30–80 sec and 5–20 sec for steels with 0.18, 0.34, and 0.56% C under the same conditions. 2. The results obtained are needed to investigate the effect of the basic stages of recrystallization in deformed austenite on the properties of the steel resulting from HTTMT, which in turn is needed for proper development of HTTMT technology.

Journal ArticleDOI
TL;DR: The relationship between the ultimate tensile and yield strength values and the structure is explained using the Petch equation as discussed by the authors, in which, in the case of a lamellar structure, the size of colonies with the same direction of lamellas has been adopted as the characteristic grain size.
Abstract: 1. The Interrelation between the ultimate tensile and yield strength values and the structure.of VTZ-1 alloy may be explained using the Petch equation, in which, in the case of a lamellar structure, the size of colonies with the same direction of lamellas and in the case of an equiaxed structure, the size of α-grains has been adopted as the characteristic grain size. 2. The values of the parameters σ0 and, especially, of ky, for the lamellar structure are larger than for the equiaxed structure which in the case of the colonies of identical size and α-grains, accounts for the higher strength of the lamellar structure. 3. Within the temperature range 20–350 °C the friction stress σ0 decreases while at higher temperatures (up to 600 °C) it remains constant. The parameter ky in the temperature range 20–600 °C follows a curve having a maximum at 350 °C. 4. For the limiting values of the long-term strength and fatigue and for plasticity properties of the alloy with a lamellar structure this relationship is similar to the Petch equation. 5. By reducing the size of colonies it is possible to improve the mechanical properties of VTZ-1 alloy rods with a lamellar structure.