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1.
In the present investigation, the focus is on dynamic coarsening of the equilibrium ϑ phase in an Al-4wt pct Cu alloy. For this purpose, specimens containing a uniform ϑ particle distribution have been produced and deformed in compression at two different temperatures (200 °C and 250 °C) and
strain rates in the ranges of 200 °C to 250 °C and 10−5 to 10−2 s−1, respectively. The particle size distribution measurements performed in a scanning microscope in back-scattered mode demonstrated
a double peak behavior depending on temperature: at the lowest test temperature, the dynamic coarsening is enhanced at the
highest strain rate, while at 250 °C, the coarsening seems to be affected by crushing of small and medium size particles during
straining. 相似文献
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《钢铁冶炼》2013,40(5):349-352
AbstractHot rolling of medium carbon steel bars using a prototype mill and numerical analyses were carried out to examine quantitatively the effect of temperature and strain throughout rolling on the final grain size of the product. Cross-sections of the rolled bars were subjected to optical microscopy to investigate the effect of the instantaneous decrease in temperature owing to contact with the roll groove on grain coarsening in the vicinity of the bar surface. By analysing the grain size after rolling, the temperature history throughout rolling, and the equivalent plastic strain after rolling, it was found that the instantaneous decrease in temperature owing to contact did not affect grain coarsening unless the final values of the temperature and strain fell within a narrow band of values meeting the criteria for grain coarsening. Referring to both the present results and the authors' previous studies, criteria have been established for the prevention of grain coarsening in steel bar sizing operations. 相似文献
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V. M. Pelepelin 《Powder Metallurgy and Metal Ceramics》1965,4(11):933-938
Summary A study was made of the effect of prior plastic deformation on the hardness, strength, coercive force, and electrical resistivity of tungsten carbide-cobalt hard alloys containing 10–25% cobalt. Plastic deformation decreases the hardness of the alloys. Up to a deformation of about 5–6%, all the alloys investigated showed a marked drop in hardness. Further deformation did not decrease the hardness of alloy VK25; for the alloys with lower cobalt contents, the hardness decrease was less pronounced. 相似文献
7.
H. I. Danilenko A. N. Demidik Yu. N. Podrezov A. P. Rachek 《Powder Metallurgy and Metal Ceramics》1991,30(9):780-784
Conclusions Structurai evolution in powder material is subject to the laws of deformation for cast bcc metals.The fracture energy and cold-brittleness temperature are sensitive to the structural state of the material: change in this predetermines the changes in the fracture energy and cold-brittleness temperature.The nature of the change in fracture energy with degree of deformation is independent of the method of production of the material (cast or powder) and the rolling temperature (below the recrystallization temperature): at low deformations the fracture energy decreases (=0–15%); following this it increases upon formation of a cell structure (=15–30%). With further increase in the degree of deformation (=30–40%) the fracture energy decreases, upon transition to a misoriented cell structure the fracture energy in the rolling plane decreases, but in the transverse plane increases.Translated from Poroshkovaya Metallurgiya, No. 9(345), pp. 74–79, September, 1991. 相似文献
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轧制塑性变形对W-Cu复合材料组织性能影响 总被引:1,自引:0,他引:1
对不同Cu含量[20%~50%(质量分数)]的热挤压后的W-Cu合金坯料进行轧制,通过对比得出最佳轧制工艺参数,并制备出微观组织均匀、致密度高、性能优异的W-Cu合金板材。结果表明:轧制力随着道次轧下量的增加而逐渐增大,并且当一次轧下量超过60%时,轧制力急剧增加;随着轧制变形量的增加,Cu相发生变形,W相形状基本不发生变化,但W相有细化的趋势;轧制变形能在保持W-Cu合金热挤压后高组织均匀性、高致密度、高性能的基础上获得薄板甚至是箔材。 相似文献
10.
V. F. Bashev N. E. Zhitnik V. A. Ivanov D. A. Rybalka Yu. A. Tkachenko 《Russian Metallurgy (Metally)》2011,(1):85-88
The specific features of structure formation in Pb-Ca-Sn alloys intended for battery current leads are considered. The effect
of plastic deformation on the mechanical properties and the fine-structure parameters in Pb-0.1% Ca-0.3% Sn and Pb-0.05% Ca-1.1%
Sn alloys is studied. The influence of the initial structure on the mechanical properties and the fine-structure parameters
of the alloys is shown, and the variation of the alloy properties under plastic deformation is demonstrated. 相似文献
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《Acta Metallurgica Materialia》1990,38(8):1573-1580
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A. L. Maksimenko O. V. Mikhailov M. B. Shtern 《Powder Metallurgy and Metal Ceramics》1992,31(5):381-385
Translated from Poroshkovaya Metallurgiya No. 5(353), pp. 13–18, May, 1992. 相似文献
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Influence of the temperature on the plastic deformation in TiAl 总被引:1,自引:0,他引:1
L. Parrini 《Metallurgical and Materials Transactions A》1999,30(11):2865-2873
A new alloy, Ti-48.6Al-1.9Cr-1.9Nb-1B, with a near-equiaxed γ microstructure and with a lamellar microstructure is investigated by compression tests between 20 and 800 °C and transmission
electron microscopy (TEM). The yield stress exhibits no anomaly as a function of the temperature, while an anomaly, related
to strain hardening, is found at 400 °C in the hardening rate and the activation volume for both the lamellar and nonlamellar
structure. Above 700 °C, a change in the deformation mechanism occurs and the material becomes remarkably softer. The TEM
micrographs highlight the importance of ordinary dislocation motion for both structures at all temperatures. The comparison
with previously reported TEM observations on single-phase TiAl alloys shows definitely that the density of ordinary dislocations
is higher in the investigated two-phase TiAl alloy deformed at room temperature. Also, the presence of the lamellar interfaces
drastically changes the mechanical properties of the alloy and the deformation mechanism. In contrast to the nonlamellar samples,
superdislocations are rare, and twinning is very frequent in the lamellar structure. 相似文献
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《Acta Metallurgica Materialia》1994,42(3):937-945
The fact that plastic deformation is controlled by thermally activated processes leads to the physically rigorous conclusions that the mechanisms are defined either by a single rate constant or by the kinetics combination of rate constants. For the determination of the kinetics—that is, for the establishment of the functional relation of the stress dependence of the work, experiments have to be carried out. When the test results are plotted in the coordinate systems of logarithm of strain rate vs linear stress, also logarithm of strain rate versus linear reciprocal temperature, the behavior exhibited by the two plots defines the nature of the stress dependence of the work. The kinetics analysis of the two representations leads to the functional expression of the constitutive law in physically exact and rigorous expressions. Applications to typical mechanisms are discussed: plasticity limited by discrete obstacles; lattice diffusion controlled creep; dislocation core diffusion controlled creep; plasticity limited by lattice resistance. 相似文献
16.
R. E. Gliner E. B. Katyukhin D. R. Zhalilov V. V. Vybornov V. A. Pryanichnikov 《Russian Metallurgy (Metally)》2016,2016(13):1298-1302
A technique for determining the degree of reduction upon forming by cold bulk shaping has been proposed. The technique is based on a comparison of the measurement data on the hardness of a cold-worked metal with that of the same metal subjected to a compression test at a certain strain intensity. The technique has been tested in technological operations of reduction and thread rolling. 相似文献
17.
The plastic deformation of TiAl 总被引:1,自引:0,他引:1
D. Shechtman M. J. Blackburn H. A. Lipsitt 《Metallurgical and Materials Transactions B》1974,5(6):1373-1381
The deformation substructure of TiAl (Llo type ordered lattice) tested in compression, and the factors determining it were
investigated. Two types of dislocations take part in the plas-tic deformation, namely a/2 [110] and a/2 [Oil]. The latter
type will disorder the Llo super-lattice and therefore would be expected to move in pairs as superdislocations. Some obser-vations
are essentially in agreement with the predictions, however the large proportion and morphology of a/2 [O1l] dislocations observed
was unexpected. Twins of the [112] (111) type play an important role in the deformation of the alloy, and the early stages
of their formation have been recorded. Finally, equi-Schmid factor lines have been constructed in an attempt to evaluate the
importance of the sense of the applied stress on the deformation capability of the alloy.
Formerly visiting Scientist at the Aerospace Research Laboratories 相似文献
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I. N. Chaporova L. E. Pivovarov V. A. Ivensen O. N. Éiduk T. A. Sultanyan A. V. Varaksina R. F. Korotkova V. A. Chistyakova 《Powder Metallurgy and Metal Ceramics》1969,8(5):389-393
Summary The structural picture is established of strain propagation in the carbide and cobalt phases in VK6 and VK50 hard alloys at loads approaching the yield point of the alloys. Electron-microscopical investigation reveals slip bands in the carbide phase at stresses close to, or equal to, the yield point of the alloys. This is observed both in the low-cobalt VK6 and the high-cobalt VK50 alloys, which may be attributed to their structures being similar in that they both exhibit continuous WC-WC grain contacts.Translated from Poroshkovaya Metallurgiya, No. 5 (77), pp. 63–68, May, 1969. 相似文献
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《Acta Metallurgica Materialia》1994,42(4):1383-1388
The effects of rolling, bending and high pressure working on the structure and microhardness of Fe, FeNi and Co based metallic glasses have been investigated. Some special methods of specimen deformation and microhardness measurement were used. The structure has beeninvestigated by X-ray analysis and positron annihilation methods. A large importance of structural relaxation process occurring at room temperature during some hours after deformation has been established. The correlation between structural changes and those of mechanical properties after deformation has been found. The strain hardening and strain softening of metallic glasses has been found to depend upon the pattern of stressed state under the deformation. 相似文献