High temperature impression creep behavior and microstructures of wrought ZM21 magnesium alloy

2021 ◽  
pp. 146442072110476
Author(s):  
D Ebenezer ◽  
SR Koteswara Rao ◽  
S Vijayan ◽  
R Rajeswari
Keyword(s):  
Activation Energy ◽  
High Temperature ◽  
Magnesium Alloy ◽  
Creep Behavior ◽  
Elevated Temperatures ◽  
Automotive Electronics ◽  
Impression Creep ◽  
Aerospace Applications ◽  
Power Law Creep ◽  
Zm21 Magnesium Alloy

Mg-Zn alloys are promising candidates for their application in automotive, electronics and aerospace applications. For their successful application, one of the performance parameters that needs to be evaluated is their creep behavior at elevated temperatures. Hence this paper evaluates the high temperature creep behavior of wrought ZM21 magnesium alloy by impression test The tests were performed under constant temperature and stress. A flat ended cylindrical punch was used to create impressions. The temperature was varied between 398 K and 598 K while the stresses were varied from 200 MPa to 500 MPa (normalized stress: 0.014 ≤  σimp/ G ≥ 0.032). A power-law creep deformation was assumed to calculate creep exponent and activation energy using the steady state minimum impression velocity obtained from impression tests. The creep behavior was analyzed with the help of impression creep curves and plastic deformation was analyzed with the help of micrographs. It was found that creep exponent varied between 4.5 and 6 and activation energy between 73.28 and 113.35 kJ/mol were obtained. From the study it was concluded that the creep mechanism involved was pipe-diffusion-controlled dislocation climb.

ALCOA ALUMINUM ALLOY 7050

Alloy Digest ◽  
1990 ◽  
Vol 39 (1) ◽  
Keyword(s):  
Corrosion Resistance ◽  
Aluminum Alloy ◽  
High Temperature ◽  
Magnesium Alloy ◽  
Stress Corrosion Cracking ◽  
Heat Treating ◽  
Thin Sections ◽  
Aerospace Applications ◽  
Temperature Performance ◽  
Aluminum Company

Abstract ALCOA ALUMINUM ALLOY 7050 is an aluminum-zinc-copper-magnesium alloy with a superior combination of strength, stress-corrosion cracking resistance and toughness, particularly in thick sections. In thin sections it also possesses an excellent combination of properties that are important for aerospace applications. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as creep. It also includes information on low and high temperature performance, and corrosion resistance as well as forming, heat treating, and joining. Filing Code: Al-233. Producer or source: Aluminum Company of America. Originally published as Aluminum 7050, January 1979, revised January 1990.

Hot Working of the ZEK200 Magnesium Alloy

2008 ◽  
Vol 604-605 ◽  
pp. 212-222 ◽  
Author(s):  
S. Spigarelli ◽  
Mohamad El Mehtedi ◽  
P. Ricci
Keyword(s):  
Activation Energy ◽  
High Temperature ◽  
Magnesium Alloy ◽  
Direct Chill ◽  
Equivalent Strain ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Torsion Testing ◽  
A Value ◽  
Complete Recrystallization

The high temperature workability of the ZEK200 Mg-alloy produced by Direct Chill casting (DC) was investigated by torsion testing between 200 and 450°C. The alloy exhibited a higher strength and a slightly lower equivalent strain to fracture than AZ31 and ZM21 produced by DC. The calculation of the constitutive equation gave a value of the activation energy for high temperature deformation close to 175 kJ/mol, in line with those calculated by following the same procedure in AZ31 and ZM21. Partial or complete recrystallization of the deformed structure was observed at 350 and 400°C respectively. Grain growth occurred after recrystallization in the samples tested at 450°C.

Interface Controlled Diffusional Creep of Cu + 2.8 at.% Co Solid Solution

2012 ◽  
Vol 322 ◽  
pp. 33-39 ◽  
Author(s):  
Sergei Zhevnenko ◽  
Eugene Gershman
Keyword(s):  
Activation Energy ◽  
Solid Solution ◽  
Surface Tension ◽  
High Temperature ◽  
Creep Behavior ◽  
Pure Copper ◽  
Diffusional Creep ◽  
High Temperature Creep ◽  
Temperature Range ◽  
Different Temperatures

High-temperature creep experiments were performed on a Cu-2.8 ат.% Co solid solution. Cylindrical foils of 18 micrometers thickness were used for this purpose. Creep tests were performed in a hydrogen atmosphere in the temperature range of about from 1233 K to 1343 K and at stresses lower than 0.25 MPa. For comparison, a foil of pure copper and Cu-20 at.% Ni solid solution were investigated on high temperature creep. Measurements on the Cu foil showed classical diffusional creep behavior. The activation energy of creep was defined and turned out to be equal 203 kJ/mol, which is close to the activation energy of bulk self-diffusion of copper. There was a significant increase in activation energy for the Cu-20 at.% Ni solid solution. Its activation energy was about 273 kJ/mol. The creep behavior of Cu-Co solid solution was more complicated. There were two stages of diffusional creep at different temperatures. The extremely large activation energy (about 480 kJ/mol) was determined at relatively low temperature and a small activation energy (about 105 kJ/mol) was found at high temperatures. The creep rate of Cu-Co solid solution was lower than that of pure copper at all temperatures. In addition, the free surface tension of Cu-2.8 ат.% Co was measured at different temperatures from 1242 K to 1352 K. The surface tension increases in this temperature range from 1.6 N/m to 1.75 N/m. There were no features on the temperature dependence of the surface tension.

scholarly journals Microstructure and impression creep characteristics Al-9Si-xCu aluminum alloys

10.30544/101 ◽  
2015 ◽  
Vol 21 (2) ◽  
pp. 115-126 ◽  
Author(s):  
Mohsen Yousefi ◽  
Mehdi Dehnavi ◽  
S.M. Miresmaeili
Keyword(s):  
Activation Energy ◽  
Aluminum Alloys ◽  
Intermetallic Compound ◽  
Stress Exponent ◽  
Creep Behavior ◽  
Eutectic Phase ◽  
Dislocation Creep ◽  
Impression Creep ◽  
Pipe Diffusion ◽  
Creep Characteristics

The effects of 1.5, 2.5 and 3.5 wt.% Cu additions on the microstructure and creep behavior of the as-cast Al-9Si alloy were investigated by impression tests. The tests were performed at temperature ranging from 493 to 553 K and under punching stresses in the range 300 to 414 MPa for dwell times up to 3000 seconds. The results showed that, for all loads and temperatures, the Al–9Si–3.5Cu alloy had the lowest creep rates and thus, the highest creep resistance among all materials tested. This is attributed to the formation of hard intermetallic compound of Al2Cu, and higher amount of α-Al2Cu eutectic phase. The stress exponent and activation energy are in the ranges of 5.2- 7.2 and 115 -150 kJ/ mol, respectively for all alloys. According to the stress exponent and creep activation energies, the lattice and pipe diffusion- climb controlled dislocation creep were the dominant creep mechanism.

scholarly journals High Temperature Silicon Integrated Circuits and Passive Components for Commercial and Military Applications

1998 ◽  
Author(s):  
Richard R. Grzybowski ◽  
Ben Gingrich
Keyword(s):  
High Temperature ◽  
Integrated Circuits ◽  
Integrated Circuit ◽  
Elevated Temperatures ◽  
Silicon On Insulator ◽  
Passive Component ◽  
Oil Well ◽  
Automotive Electronics ◽  
Passive Components ◽  
Silicon Integrated Circuits

Advances in silicon-on-insulator (SOI) integrated circuit technology and the steady development of wider band gap semiconductors like silicon carbide are enabling the practical deployment of high temperature electronics. High temperature civilian and military electronics applications include distributed controls for aircraft, automotive electronics, electric vehicles and instrumentation for geothermal wells, oil well logging and nuclear reactors. While integrated circuits are key to the realization of complete high temperature electronic systems, passive components including resistors, capacitors, magnetics and crystals are also required. This paper will present characterization data obtained from a number of silicon high temperature integrated evaluated over a range of elevated temperatures and aged at a selected high temperature. This paper will also present a representative cross section of high temperature passive component characterization data for device types needed by many applications. Device types represented will include both small signal and power resistors and capacitors. Specific problems encountered with the employment of these devices in harsh environments will be discussed for each family of components. The goal in presenting this information is to demonstrate the viability of a significant number of commercially available silicon integrated circuits and passive components that operate at elevated temperatures as well as to encourage component suppliers to continue to optimize a selection of their product offerings for operation at higher temperatures. In addition, systems designers will be encouraged to view this information with an eye toward the conception and implementation of reliable and affordable high temperature systems.

Impression Creep Behavior of Atmospheric Plasma-Sprayed and Hot Pressed MoSi2/Si3N4

1997 ◽  
Author(s):  
K.J. Hollis ◽  
D.P. Butt ◽  
R.G. Castro
Keyword(s):  
High Temperature ◽  
Grain Boundary ◽  
Creep Behavior ◽  
Grain Boundary Sliding ◽  
Atmospheric Plasma ◽  
Second Phase ◽  
Impression Creep ◽  
Creep Mechanisms ◽  
Boundary Sliding ◽  
Plasma Sprayed

Abstract The use of MoSi2 as a high temperature oxidation resistant structural material is hindered by its poor elevated temperature creep resistance. The addition of second phase Si3N4 holds promise for improving the creep properties of MoSi2 without decreasing oxidation resistance. The high temperature impression creep behavior of atmospheric plasma sprayed (APS) and hot pressed (HP) MoSi2/Si3N4 composites was investigated. Values for steady state creep rates, creep activation energies, and creep stress exponents were measured. Grain boundary sliding and splat sliding were found to be the dominant creep mechanisms for the APS samples while grain boundary sliding and plastic deformation were found to be the dominant creep mechanisms for the HP samples.

Comparison of the High-Temperature Deformation of Alumina-Zirconia and Alumina-Zirconia-Mullite Composites

2005 ◽  
Vol 20 (1) ◽  
pp. 13-17 ◽  
Author(s):  
Tiandan Chen ◽  
Martha L. Mecartney
Keyword(s):  
Activation Energy ◽  
High Temperature ◽  
Strain Rate ◽  
Stress Exponent ◽  
Creep Behavior ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Reactive Processing ◽  
Lower Activation ◽  
Lower Activation Energy

An alumina-based ceramic codispersed with 15 vol% zirconia and 15 vol% mullite (AZM) was synthesized by reactive processing, and the creep behavior was compared to alumina with 30 vol% zirconia (AZ). Constant stress compressive creep behavior for AZM exhibited a stress exponent of 2 and an activation energy of 770 KJ/mol, while a similar stress exponent but lower activation energy of 660 KJ/mol was found for AZ. The strain rate of AZM, however, was more than twice that of the AZ under the same deformation conditions, indicating a better potential for superplastic shape forming.

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