A Study on Microstructures and Creep Behaviors in the Mg-3Sr-xY Alloys

2011 ◽  
Vol 418-420 ◽  
pp. 602-605
Author(s):  
Ming Hu ◽  
Han Fei ◽  
Jing Gao ◽  
Fang Fang Zhao
Keyword(s):  
Dynamic Recrystallization ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Reduction Method ◽  
Creep Mechanism ◽  
Creep Limit ◽  
Creep Properties ◽  
Second Phases ◽  
Thermal Extrusion

In this paper, the author successfully fabricated Mg-3Sr-xY alloys by melting-leaching reduction method using SF6 and N2 as protected gas. The microstructures of the Mg-3Sr-xY alloys were investigated in details，and the results showed that Mg-3Sr-xY alloys are composed of dendrite α-Mg and eutectic α-Mg and Mg17Sr2 and Mg24Y5 particulates, the second phases distribute in the α-Mg dendrites and interdendrites. The fiber microstructures form after thermal extrusion and the dynamic recrystallization occurs. In Mg-3Sr-xY alloy, the tensile strengths, the yield strengths and elongation rates increase firstly, reach the peak values, decrease with the increasing in Y content. Mg-3Sr-xY alloy have the best mechanics properties, including yield strengths and ultimate strengths and elongation rates and creep properties by the addition of 0.6%Y content. The tensile behaviors at elevated temperatures are accord to general laws for the metals at room temperature. The Mg-3Sr-xY alloys with 0.4-1.0% Y are of best creep limit. The dislocation sliding and climbing is the main creep mechanism for Mg-3Sr-0.6Y alloys.

Effect of Ca and Sr Content on Elevated Temperatures Mechanical Properties of a Cast AZ91 Magnesium Alloy

2007 ◽  
Vol 26-28 ◽  
pp. 141-144
Author(s):  
Ippei Takeuchi ◽  
Kinji Hirai ◽  
Yorinobu Takigawa ◽  
Tokuteru Uesugi ◽  
Kenji Higashi
Keyword(s):  
Mechanical Properties ◽  
Magnesium Alloy ◽  
Creep Resistance ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Tensile Tests ◽  
Az91 Magnesium Alloy ◽  
Additional Amount ◽  
Az91 Magnesium ◽  
Second Phases

The effect of Ca and Sr content on the microstructure and mechanical properties of a cast AZ91 magnesium alloy is investigated. Ca and Sr additions in AZ91 magnesium alloy are expected high creep resistance. The microstructure of the alloy exhibits the dendritic α-matrix and the second-phases forming networks on the grain boundary. Tensile tests at elevated temperatures between 448 and 523K reveal that the creep resistance was improved with increasing the additional amount of Ca, especially more than 1.0wt%. From the perspective of grain refinement effect, it is expected that the additions of Ca and Sr to AZ91 magnesium alloy not only improve creep resistance but also improve mechanical properties at room temperature.

Microstructures, Mechanical and Creep Properties of Rapidly Solidification/Powder Metallurgy Mg-6wt.%Zn Alloys with 5wt.%Ce and 1.5wt.%Ca Additions

2016 ◽  
Vol 861 ◽  
pp. 253-263
Author(s):  
Tao Zhou ◽  
Deng Hui Song ◽  
Zhen Hua Chen
Keyword(s):  
Compressive Strength ◽  
Powder Metallurgy ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Hot Extrusion ◽  
Creep Properties ◽  
High Compressive Strength ◽  
Rapidly Solidification ◽  
Twin Roll ◽  
Thermal Stability Of

Rapidly solidification/powder metallurgy (RS/PM) Mg-6Zn, Mg-6Zn-5Ce and Mg-6Zn-5Ce-1.5Ca (wt.%) alloys were produced via hot extrusion with RS powders, produced by atomization-twin roll quenching. Microstructures, mechanical and creep properties of the alloys were investigated. The results showed that for the Mg-6Zn alloys with 5wt.%Ce and 1.5wt.%Ca additions, the microstructures of the alloys were gradually refined, which caused the strength of the alloy at room temperature to increase remarkably, especially for the RS/PM Mg-6Zn-5Ce-1.5Ca alloy, exhibited a high compressive strength of 394MPa at room temperature. At elevated temperatures, due to the fine and stable intermetallic compounds i.e. MgxZnyCez and MgxZnyCez-(Ca) phases were formed for the Mg-6Zn-5Ce alloy and Mg-6Zn-5Ce-1.5Ca alloys, respectively, and the thermal stability of the ternary phase was a little lower than that of the quaternary phase because of the dissolving of Ca into the MgxZnyCez phase, the mechanical and creep properties at elevated temperatures increased remarkably with Ce and Ca additions, especially for the RS/PM Mg-6Zn-5Ce-1.5Ca alloy, which exhibited a high compressive strength of 258MPa at 200°C, and the minimum creep rate was decreased about 2 times, compared with that of the Mg-6Zn-5Ce alloy.

Microstructural Studies of the Deformation of TiAl Alloys

1988 ◽  
Vol 133 ◽  
Author(s):  
Ernest L. Hall ◽  
Shyh-Chin Huang
Keyword(s):  
Room Temperature ◽  
Single Phase ◽  
Elevated Temperatures ◽  
Alloy Composition ◽  
Two Phase ◽  
Tial Alloys ◽  
Second Phases ◽  
Bend Tests ◽  
Microstructural Studies ◽  
Strength And Ductility

ABSTRACTThe mechanical behavior and microstructures of TiAl alloys after tensile and bend tests at room temperature and elevated temperatures were studied. The results for two-phase Ti52Al48 alloys are compared with those of single phase Ti48Al52, and the effect of adding 3 at. pct. vanadium as a substitute for Ti in these two alloys is considered. It is shown that Ti52Al48 has greater strength and ductility than Ti48Al52 at room temperature and elevated temperatures up to 871°C (1600°F). Adding vanadium increases the ductility of both binary alloys. The microstructure of the Ti52Al48 alloy deformed at room temperature contains primarily twins and 1/2<110> easy slip dislocations, whereas the similar Ti48Al52 sample exhibits superdislocations and associated pinned faulted dipoles. If these samples are deformed at 540°C (1000°F) or above, the Ti52Al48 exhibits extensive twinning, and the pinned faulted dipoles in the Ti48Al52 sample disappear. The vanadium additions do not noticeably change the deformation microstructure at room temperature. It is suggested that the strength and ductility of these alloys may be controlled by tetragonality, bonding, interstitial element, and grain size effects, which in turn are affected by the presence of second phases and by the alloy composition.

scholarly journals Creep Behavior of Near α High Temperature Ti-6.6Al-4.6Sn-4.6Zr-0.9Nb-1.0Mo-0.32Si Alloy

2021 ◽  
Vol 8 ◽  
Author(s):  
Dongye Yang ◽  
Wenqi Tian ◽  
Xinqi Zhang ◽  
Ke Si ◽  
Jiuxiao Li
Keyword(s):  
High Temperature ◽  
Room Temperature ◽  
Creep Mechanism ◽  
Creep Properties ◽  
Microstructure Characteristics ◽  
Transmission Electron ◽  
Diffusion Controlled ◽  
Dislocation Movement ◽  
Alloy Microstructure ◽  
Applied Stresses

This study focuses on the microstructure characteristics and tensile and creep properties of a near α high temperature Ti-6.6Al-4.6Sn-4.6Zr-0.9Nb-1.0Mo-0.32Si alloy. Microstructure characteristics were quantitatively investigated using optical microscopy, scanning electron microscope, and transmission electron microscopy. Tensile properties were carried out at room and high temperature. Creep properties were detected under applied stresses ranging from 100–350 MPa at 873–973 K, respectively. Results showed that Widmanstätten microstructure was obtained after hot forged and heat treatment. The strength decreases and the elongation rises with temperature increasing. The ultimate strength and elongation were 1010 MPa, 12% at room temperature, and 620 MPa, 20% at 923 K, respectively. The steady state creep rates rise correspondingly with stress and temperature. Stress exponents are measured within the range of 3.0–3.5. Thus, the creep mechanism is diffusion-controlled viscous glide of dislocation. Ti3Al precipitates are observed. The boundaries and precipitates can obstruct dislocation movement to improve the creep properties. Fracture mechanism of creep is intergranular. The creep mechanism varied from climb of dislocation to sliding of dislocation solution.

Creep of a niobium beryllide, Nb2Be17

1993 ◽  
Vol 8 (4) ◽  
pp. 757-763 ◽  
Author(s):  
T.G. Nieh ◽  
J. Wadsworth ◽  
T.C. Chou ◽  
D. Owen ◽  
A.H. Chokshi
Keyword(s):  
Low Temperatures ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Hardness Test ◽  
Transient Creep ◽  
Test Results ◽  
Creep Properties ◽  
Dislocation Glide ◽  
Applied Stresses ◽  
Hot Hardness

A niobium beryllide, Nb2Be17, has been prepared by powder-metallurgy techniques and the mechanical properties characterized both at room and elevated temperatures. Microhardness and fracture toughness were measured at room temperature. Hardness and hot-hardness test results indicated that, although the material was brittle at low temperatures, it became plastic at elevated temperatures (>1000 °C). Creep properties of Nb2Be17 were studied at temperatures from 1250 to 1350 °C and applied stresses from 10 to 90 MPa. The stress exponent, determined from stress-change tests, was about 3, and the activation energy, determined from temperature-change tests, was about 575 kJ/mol. The creep of Nb2Be17 at high temperature is apparently controlled by dislocation glide; this proposal was supported by transient creep experiments. Comparisons have been made between the creep properties of Nb2Be17 and other intermetallics.

Mechanical Properties and Dislocation Structure of Single Crystal Cdte Deformed in Compression at 300°C

1976 ◽  
Vol 34 ◽  
pp. 592-593
Author(s):  
Ernest L. Hall ◽  
J. B. Vander Sande
Keyword(s):  
Mechanical Properties ◽  
Single Crystal ◽  
Dislocation Structure ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Strain Curve ◽  
Optical Devices ◽  
Semiconductor Compound ◽  
Wide Range ◽  
Sample Orientation

The present paper describes research on the mechanical properties and related dislocation structure of CdTe, a II-VI semiconductor compound with a wide range of uses in electrical and optical devices. At room temperature CdTe exhibits little plasticity and at the same time relatively low strength and hardness. The mechanical behavior of CdTe was examined at elevated temperatures with the goal of understanding plastic flow in this material and eventually improving the room temperature properties. Several samples of single crystal CdTe of identical size and crystallographic orientation were deformed in compression at 300°C to various levels of total strain. A resolved shear stress vs. compressive glide strain curve (Figure la) was derived from the results of the tests and the knowledge of the sample orientation.

Spherulite Structures in a Melt Spun Fe-Ni Austenitic Steel

1985 ◽  
Vol 43 ◽  
pp. 52-53
Author(s):  
G. M. Michal ◽  
T. K. Glasgow ◽  
T. J. Moore
Keyword(s):  
Austenitic Steel ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Large Range ◽  
Amorphous Structure ◽  
Nucleation And Growth ◽  
Ni Alloys ◽  
Melt Spun ◽  
Crystal Fibers ◽  
Rapidly Solidified

Large additions of B to Fe-Ni alloys can lead to the formation of an amorphous structure, if the alloy is rapidly cooled from the liquid state to room temperature. Isothermal aging of such structures at elevated temperatures causes crystallization to occur. Commonly such crystallization pro ceeds by the nucleation and growth of spherulites which are spherical crystalline bodies of radiating crystal fibers. Spherulite features were found in the present study in a rapidly solidified alloy that was fully crysstalline as-cast. This alloy was part of a program to develop an austenitic steel for elevated temperature applications by strengthening it with TiB2. The alloy contained a relatively large percentage of B, not to induce an amorphous structure, but only as a consequence of trying to obtain a large volume fracture of TiB2 in the completely processed alloy. The observation of spherulitic features in this alloy is described herein. Utilization of the large range of useful magnifications obtainable in a modern TEM, when a suitably thinned foil is available, was a key element in this analysis.

FANSTEEL 85 METAL

Alloy Digest ◽  
1981 ◽  
Vol 30 (6) ◽  
Keyword(s):  
High Temperature ◽  
Physical Properties ◽  
Creep Strength ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Base Alloy ◽  
Heat Treating ◽  
Good Combination ◽  
Bend Strength ◽  
Temperature Performance

Abstract FANSTEEL 85 METAL is a columbium-base alloy characterized by good fabricability at room temperature, good weldability and a good combination of creep strength and oxidation resistance at elevated temperatures. Its applications include missile and rocket components and many other high-temperature parts. This datasheet provides information on composition, physical properties, microstructure, hardness, elasticity, tensile properties, and bend strength as well as creep. It also includes information on low and high temperature performance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: Cb-7. Producer or source: Fansteel Metallurgical Corporation. Originally published December 1963, revised June 1981.

USS TENELON

Alloy Digest ◽  
1975 ◽  
Vol 24 (5) ◽  
Keyword(s):  
Corrosion Resistance ◽  
Elevated Temperatures ◽  
Stress Rupture ◽  
High Strength ◽  
Heat Treating ◽  
Creep Properties ◽  
United States Steel Corporation ◽  
Excellent Corrosion Resistance ◽  
Wide Range ◽  
Mild Acid

Abstract USS TENELON is a completely austenitic, nickel-free stainless steel with exceptionally high strength which is retained at elevated temperatures. It has excellent corrosion resistance in atmospheric and mild acid exposures and maintains nonmagnetic characteristics even when 60% cold reduced. It also has good stress-rupture and creep properties in the range 1200-1500 F. It has a wide range of applications. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as fracture toughness, creep, and fatigue. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: SS-311. Producer or source: United States Steel Corporation.

EASTERN STAINLESS TYPE 309S

Alloy Digest ◽  
1984 ◽  
Vol 33 (3) ◽  
Keyword(s):  
Stainless Steel ◽  
Heat Exchangers ◽  
Elevated Temperatures ◽  
Heat Treating ◽  
Scaling Up ◽  
Oil Refining ◽  
Steel Company ◽  
High Alloy ◽  
Creep Properties ◽  
Refining Equipment

Abstract EASTERN STAINLESS TYPE 309S is a heat-resisting grade of stainless steel. Because of its high alloy content, it resists scaling up to 2000 F. It also has good tensile and creep properties and elevated temperatures. Type 309S has good ductility and malleability; therefore, difficult shapes and structures can be fabricated easily and it can be machined readily. It can be welded easily and gives strong, ductile welds. Some of its many applications are annealing boxes, boiler baffles, dryers, furnace parts, heat exchangers and oil-refining equipment. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as creep. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: SS-441. Producer or source: Eastern Stainless Steel Company.

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