Evolution Of Cast Research Articles

Comparative Study on Compression Deformation Behaviors of Cast and Extruded AZ31 Alloys

Compression properties, microstructure evolution and deformation behaviors of cast and extruded AZ31 alloys are investigated. The results show that compressive yield stress, ultimate strength and ultimate compression ratio between extruded and cast AZ31 alloy are quite different. The yielding pattern of as-cast AZ31 alloy is continuous, and the yield pattern of extruded AZ31 alloy demonstrate an obvious yielding plateau mode. The angle between the fractures and specimens axis of as-cast and extruded AZ31 alloy is about 45°. A mass of reliefs and damage can be found on the specimen surface of as-cast AZ31 alloy and the twinning is main deformation sign in as-cast AZ31 alloy as seen a rough surface. The slip activity might be a predominant deformation mechanism in extruded AZ31 alloy judged by smooth surface after fracture.

Microstructure and mechanical properties of Mg–Al–Mn–Ca alloy sheet produced by twin roll casting and sequential warm rolling

Microstructural evolution and mechanical properties of twin roll cast (TRC) Mg–3.3 wt.%Al–0.8 wt.%Mn–0.2 wt.%Ca (AM31 + 0.2Ca) alloy strip during warm rolling and subsequent annealing were investigated in this paper. The as-TRC alloy strip shows columnar dendrites in surface and equiaxed dendrites in center regions, as well as finely dispersed primary Al 8Mn 5 particles on interdendritic boundaries which result in the beneficial effect on microstructural refinement of strip casting. The warm rolled sheets show intensively deformed band or shear band structures, as well as finely and homogeneously dispersed Al–Mn particles. No evident dynamic recrystallization (DRX) takes place during warm rolling process, which is more likely attributed to the finely dispersed particle and high solid solution of Al and Mn atoms in α-Mg matrix. After annealing at 350 °C for 1 h, the warm rolled TRC sheets show fine equiaxed grains around 7.8 μm in average size. It has been shown that the present TRC alloy sheet has superior tensile strength and comparative elongation compared to commercial ingot cast (IC) one, suggesting the possibility of the development of wrought magnesium alloy sheets by twin roll strip casting processing. The microstructural evolution during warm rolling and subsequent annealing as well as the resulting tensile properties were analyzed and discussed.

Microstructure evolution of cast Al-Si-Cu alloys in solution treatment

To develop a software to predict the evolution of microstructure and the development of mechanical properties during the heat treatment of cast aluminum alloys, we modeled the redistribution of solute during the solution treatment of multicomponent alloys. The predictions of solidifi cation simulation software or the results of experiment provided the initial microstructure and solute distribution for simulation of heat treatment. Binary through quinary aluminum alloys with silicon, copper, magnesium, and iron were modeled. The basic model assumed local equilibrium (no undercooling due to nucleation or growth) and computed diffusion in the solid constituents during solidification. The evolution of microstructure during solution treatment was followed by qualitative and quantitative metallography. The results of simulation for the ternary alloy Al-7%Si-3.5%Cu were compared to experimental observation.

Microstructural Evolution of Cast Mg-Al-Ca Alloy during Friction Stir Processing

A thixomoulded magnesium alloy containing thermally stable Al2Ca phase was friction stir processed, and its microstructure and mechanical property were investigated. In friction stir zone, the cast structure of the base metal is replaced by fine magnesium grains containing fine dispersoides of Al2Ca. Due to the refined grain size of 0.8-1 μm, hardness of friction stir zone is higher than that of base metal. Texture was developed at top and bottom surfaces, (0002) being parallel to the plate surface, whereas (0001) plane is randomly oriented in the center of friction stir zone.

Effect of precipitation on rolling texture evolution in continuous cast AA 3105 aluminum alloy

The texture evolution of continuous cast (CC) AA 3105 aluminum alloy during cold rolling was investigated by X-ray Bragg diffraction. The influence of the precipitation state on the texture evolution during rolling was determined. The results show that the precipitates in a CC AA 3105 aluminum alloy affect the texture evolution during rolling. As the amount of precipitates increases and the size of precipitates decreases, the rate of disappearance of the cube, r-cube, and remainder components and the rate of formation of the β fiber decrease. The presence of large precipitates in a CC AA 3105 aluminum alloy hardly affects the texture evolution.

Effect of intermediate heat treatment on microstructure and texture evolution of continuous cast Al-Mn-Mg alloy sheet

The microstructure and crystallographic texture evolution of continuous-cast, hot-rolled Al-Mn-Mg alloy sheet during cold rolling and subsequent annealing was investigated. All specimens cut from the as-received sheet were cold rolled and subsequently annealed, with some of these specimens receiving an intermediate heat treatment (IHT) prior to cold rolling. It was found that the degree of deformation and temperature of the annealing had a significant effect on the final grain size and texture of the sheet specimens, respectively. Furthermore, the IHT altered the development of the microstructure and texture of the final sheet specimens when compared to similarly produced specimens without it. For the sheet specimens without the IHT, a severely elongated grain structure was found in which the texture was dominated by a strong P orientation {011} , despite the fact that the specimen was completely recrystallized. In contrast, specimens receiving the same cold rolling and annealing conditions but with the IHT had an equiaxed grain structure with a sharp Cube orientation {001} . Counterbalancing the deformation textures from rolling with a sharp Cube orientation from annealing may lead to reduced earing behavior of CC Al-Mn-Mg alloy sheet products during deep drawing applications.

Relativity: the special and general theory

A handsome annotated edition of Einstein's celebrated book on relativity After completing the final version of his general theory of relativity in November 1915, Albert Einstein wrote Relativity. Intended for a popular audience, the book remains one of the most lucid explanations of the special and general theories ever written. This edition of Einstein's celebrated book features an authoritative English translation of the text along with commentaries by Hanoch Gutfreund and Jurgen Renn that examine the evolution of Einstein's thinking and cast his ideas in a modern context. Providing invaluable insight into one of the greatest scientific minds of all time, the book also includes a unique survey of the introductions from past editions, covers from selected early editions, a letter from Walther Rathenau to Einstein discussing the book, and a revealing sample from Einstein's original handwritten manuscript.

Texture evolution of continuous cast and direct chill cast AA 3003 aluminum alloys during cold rolling

The texture evolution of continuous cast (CC) and direct chill cast (DC) AA 3003 aluminum alloys during cold rolling was investigated by X-ray diffraction. The relationship between texture volume fractions and rolling true strain was described quantitatively by mathematical formulae. The effect of processing method (CC vs. DC) on texture evolution was determined.

Tradition and Change in Greek Shadow Theater

GREEK SHADOW THEATER, which is primarily an urban phenomenon, was largely ignored until recently by folklorists, who focused their attention almost exclusively on culture of rural Greece. The decades of 1960s and 1970s, however, witnessed a remarkable surge in interest in shadow theater.' Much attention was devoted to link between shadow theater and ancient comedy, relationship between and Turkish traditions of shadow theater, and Hellenization of shadow theater in 19th century.2 Works in latter area focused on such topics as evolution of full cast of traditional characters and development of complete repertoire of classical plays. In stressing importance of shadow theater, folklorists have claimed that Karagiozis, poor, hungry trickster, with his hunchback, bare feet, and long arm, who has come to personify tradition of shadow theater, is the genuine stereotype of common Greek (Zarikos 1976:75), the only genuine expression of modern reality and the voice of modern (Trezou 1976:62). However, while popular and scholarly interest in shadow theater was increasing dramatically, tradition itself was undergoing drastic, and what many considered disturbing, changes. Well-known puppeteers were growing old, and no young people were taking their place. Fewer and fewer puppeteers were traveling through Greece giving performances in small cities and towns, while open-air theaters in large cities were being forced to close, to make way for apartment buildings and stores. Furthermore, live shadow theater performances were declining in popularity because of increased competition from movie theaters and television. Puppeteers recorded plays on long-playing records and gave short weekly performances for children on national television. Comic booklike pamphlets, orfiladhia,3 containing shadow theater plays were published inexpensively and anonymously and were advertised as the indispensable companion of every child. Karagiozis, then, had taken his place beside Mickey Mouse, Davy Crockett, and other comic book characters on shelves of kiosks and stationery stores throughout Greece. The reaction of folklorists to entry of shadow theater plays