Plastic deformation of single glide oriented Cu–2 to 15at.%Al crystals at elevated temperatures

Mg-Zn-Y alloys with long-period stacking ordered (LPSO) phases have superior strength at elevated temperatures. We studied plastic deformation and creep behavior of a Mg97Zn1Y2 (at.%) alloy. Deformation kinking of the LPSO phase plays an important role in strengthening the alloy during compression at elevated temperatures. Growth stacking faults with Zn/Y segregation can act as obstacles to non-basal slip and deformation twinning in Mg matrix. The tensile creep strain was only about 0.01% under a tensile stress of 70MPa for 100h at 200 °C, demonstrating excellent creep resistance of this alloy. Generation and motion of basal dislocations led to bending of LPSO phase during tensile creep of the Mg97Zn1Y2 (at.%) alloy. Plastic deformation in Mg grains was mostly achieved through basal slip during creep at temperatures below 200 °C, while non-basal slip through the generation and motion of “a + c” dislocations was activated with increasing the temperature to 200 °C and above. Dissociation of dislocations and Suzuki segregation on basal planes occurred widely in Mg matrix, which hindered dislocation motion and thus played an important role in preventing Mg grains from softening during deformation at elevated temperatures. In addition, Cottrell atmospheres were observed along dislocations in plastically deformed LPSO phase, impeding motion of dislocations. The superior strength and creep resistance of the Mg97Zn1Y2 (at.%) alloy at elevated temperatures are thus associated with the LPSO phase, stacking faults in Mg grains, formation of Cottrell atmospheres in LPSO and occurrence of Suzuki segregation in Mg.

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Microstructure and Indentation Fracture of Dysprosium Niobate

Journal of Materials Research ◽

10.1557/jmr.2005.0202 ◽

2005 ◽

Vol 20 (6) ◽

pp. 1422-1427 ◽

Cited By ~ 1

Author(s):

Byong-Taek Lee ◽

Waltraud M. Kriven

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Plastic Deformation ◽

Room Temperature ◽

Elevated Temperatures ◽

Indentation Fracture ◽

Optical Scanning ◽

Periodic Arrays ◽

Transmission Electron ◽

Hot Hardness

The high-temperature indentation fracture and microstructures of dysprosium niobate (DyNbO4) were investigated by optical, scanning, and transmission electron microscopy (OM, SEM, and TEM). Polycrystalline samples were sintered at 1350 °C for 3 h and cut into 3 mm disks for TEM. The disks were indented in a Nikon QM (Tokyo, Japan) hot hardness indenter at room temperature up to 1000 °C. Many lamellar twins having different widths were observed by TEM as well as intergranular microcracks. The room temperature hardness was relatively low at 5.64 GPa and decreased with elevated temperatures. Crack lengths were short, showing a typical micro-cracking effect. In the sample indented at 1000 °C, dislocations in periodic arrays were evident, and their density increased markedly due to heavy plastic deformation.

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Processing of Aluminium Alloys by Severe Plastic Deformation

Materials Science Forum ◽

10.4028/www.scientific.net/msf.519-521.45 ◽

2006 ◽

Vol 519-521 ◽

pp. 45-54 ◽

Cited By ~ 2

Author(s):

Terence G. Langdon

Keyword(s):

Plastic Deformation ◽

High Pressure ◽

Severe Plastic Deformation ◽

Elevated Temperatures ◽

High Pressure Torsion ◽

Simple Procedure ◽

Superplastic Forming ◽

High Strength ◽

Ultrafine Grain ◽

Grain Sizes

Processing through the application of severe plastic deformation (SPD) has become important over the last decade because it is now recognized that it provides a simple procedure for producing fully-dense bulk metals with grain sizes lying typically in the submicrometer range. There are two major procedures for SPD processing. First, equal-channel angular pressing (ECAP) refers to the repetitive pressing of a metal bar or rod through a die where the sample is constrained within a channel bent through an abrupt angle at, or close to, 90 degrees. Second, high-pressure torsion (HPT) refers to the procedure in which the sample, generally in the form of a thin disk, is subjected to a very high pressure and concurrent torsional straining. Both of these processes are capable of producing metallic alloys with ultrafine grain sizes and with a reasonable degree of homogeneity. Furthermore, the samples produced in this way may exhibit exceptional mechanical properties including high strength at ambient temperature through the Hall-Petch relationship and a potential superplastic forming capability at elevated temperatures. This paper reviews these two procedures and gives examples of the properties of aluminum alloys after SPD processing.

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Effect of the overloading frequency on the accumulation of plastic deformation in 1Kh18N9T steel at elevated temperatures

Strength of Materials ◽

10.1007/bf01527254 ◽

1970 ◽

Vol 2 (5) ◽

pp. 496-498

Author(s):

E. A. Antipov

Keyword(s):

Plastic Deformation ◽

Elevated Temperatures ◽

1Kh18n9t Steel

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THE PROPERTIES OF BULK ULTRAFINE-GRAINED METALS PROCESSED THROUGH THE APPLICATION OF SEVERE PLASTIC DEFORMATION

International Journal of Modern Physics Conference Series ◽

10.1142/s2010194512002164 ◽

2012 ◽

Vol 05 ◽

pp. 299-306

Author(s):

TERENCE G. LANGDON

Keyword(s):

Plastic Deformation ◽

Severe Plastic Deformation ◽

Elevated Temperatures ◽

High Pressure Torsion ◽

Superplastic Forming ◽

High Strength ◽

Basic Principles ◽

Angular Pressing ◽

Ultrafine Grained ◽

Processing Techniques

Processing through the application of severe plastic deformation (SPD) provides a very attractive tool for the production of bulk ultrafine-grained materials. These materials typically have grain sizes in the submicrometer or nanometer ranges and they exhibit high strength at ambient temperature and, if the ultrafine grains are reasonably stable at elevated temperatures, they have a potential for use in superplastic forming operations. Several procedures are now available for applying SPD to metal samples but the most promising are Equal-Channel Angular Pressing (ECAP) and High-Pressure Torsion (HPT). This paper examines the basic principles of ECAP and HPT and describes some of the properties that may be achieved using these processing techniques.

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EXPERIMENTAL INVESTIGATION OF CHALCOCITE: ANNEALING AND PLASTIC DEFORMATION AT ELEVATED TEMPERATURES

Canadian Journal of Earth Sciences ◽

10.1139/e65-010 ◽

1965 ◽

Vol 2 (2) ◽

pp. 98-117

Author(s):

Raymond Davies

Keyword(s):

Experimental Investigation ◽

Plastic Deformation ◽

Solid State ◽

Grain Growth ◽

Annealing Time ◽

Silica Glass ◽

Elevated Temperatures ◽

Recrystallization Behavior ◽

Vapor Pressures ◽

Sulfur Vapor

The recrystallization behavior and deformation of synthetic chalcocite (Cu2S) in the temperature range 400–725 °C was studied microscopically after the compound was annealed in evacuated silica glass capsules and heated under differential pressures in sealed gold capsules. The temperature of recrystallization and grain growth ascribed to the hexagonal cubic inversion, at sulfur vapor pressures much less than 1 atmosphere, was determined at 465 ± 5 °C, with annealing time of [Formula: see text].Experiments involving differential pressures of 8 000 p.s.i. show that chalcocite in the solid state becomes considerably more mobile above 563 ± 10 °C and can readily be injected as a plastic mass to form veins without preservation of deformational textures.Natural bornite and natural galena may also be injected under differential pressure at 640 °C, but some unhealed fractures remain. Flow structure is well-preserved in galena and, under certain conditions, in bornite.Mixtures of bornite and pyrite flowed and recrystallized to chalcopyrite and bornite with exsolved chalcopyrite. No evidence of flowage remained.Chalcopyrite and pyrrhotite are resistant to injection under similar differential pressures and temperatures.

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