PHENOMENOLOGICAL MODEL FOR CREEP BEHAVIOR IN Cu–8.5 at.% Al ALLOY

2007 ◽  
Vol 21 (05) ◽  
pp. 747-753
Author(s):  
M. ABO-ELSOUD
Keyword(s):  
Melting Temperature ◽  
Power Law ◽  
Creep Behavior ◽  
Phenomenological Model ◽  
Intermediate Temperature ◽  
Al Alloy ◽  
Dislocation Glide ◽  
Intermediate Temperature Range ◽  
Controlling Mechanism ◽  
Creep Regime

Creep experiments were conducted on Cu –8.5 at.% Al alloy in the intermediate temperature range, 673–873 K, corresponding to 0.46–0.72 T m , where T m is the absolute melting temperature. The present analysis reveals the presence of two distinct deformation regions (climb and viscous glide) in the plot of log [Formula: see text] versus log σ. The implications of these results on the transition from power-law to exponential creep regime are examined. The results indicated that the rate-controlling mechanism for creep is the obstacle-controlled dislocation glide. A phenomenological model is proposed, which assumes that cell boundaries with sub-grains act as sources and obstacles to gliding dislocations.

Phenomenological Model for Creep Behaviour in Cu-8.5at%Al Alloy

2006 ◽  
Vol 251-252 ◽  
pp. 89-96
Author(s):  
M. Abo-Elsoud
Keyword(s):  
Melting Temperature ◽  
Phenomenological Model ◽  
Creep Behaviour ◽  
Intermediate Temperature ◽  
Al Alloy ◽  
Dislocation Glide ◽  
Temperature Range ◽  
Intermediate Temperature Range ◽  
Controlling Mechanism ◽  
Creep Regime

Creep experiments were conducted on Cu-8.5at.% Al alloy in the intermediate temperature range from 673 to 873K, corresponding to 0.46-0.72 Tm where Tm is the absolute melting temperature. The present analysis reveals the presence of two distinct deformation regions (climb and viscous glide) in the plot of log ε vs. log σ. The implications of these results on the transition from powerlaw to exponential creep regime are examined. The results indicated that the rate controlling mechanism for creep is the obstacle-controlled dislocation glide. A phenomenological model is proposed which assumes that cell boundaries with sub-grains act as sources and obstacles to gliding dislocations.

scholarly journals Three Regions in the Power-Law Creep Regime of TiAl

1992 ◽  
Vol 33 (12) ◽  
pp. 1182-1184 ◽  
Author(s):  
Yukio Ishikawa ◽  
Kouichi Maruyama ◽  
Hiroshi Oikawa
Keyword(s):  
Power Law ◽  
Power Law Creep ◽  
Creep Regime

Relaxation of Dielectric Loss Peak over Intermediate Temperature Range in Bi 5 TiNbWO 15 Intergrowth

2009 ◽  
Vol 26 (4) ◽  
pp. 047701 ◽  
Author(s):  
Wang Wei ◽  
Wang Xiao-Juan ◽  
Zhu Jun ◽  
Mao Xiang-Yu ◽  
Chen Xiao-Bing
Keyword(s):  
Dielectric Loss ◽  
Intermediate Temperature ◽  
Loss Peak ◽  
Temperature Range ◽  
Intermediate Temperature Range

Tri-lithium borate (Li3BO3); a new highly regenerable high capacity CO2 adsorbent at intermediate temperature

2017 ◽  
Vol 5 (42) ◽  
pp. 22224-22233 ◽  
Author(s):  
Takuya Harada ◽  
T. Alan Hatton
Keyword(s):  
High Capacity ◽  
Intermediate Temperature ◽  
Lithium Borate ◽  
Next Generation ◽  
Temperature Range ◽  
Intermediate Temperature Range ◽  
Borate Oxide ◽  
Co2 Adsorbent

A lithium-borate oxide, Li3BO3, is proposed as a next generation high capacity CO2 adsorbent operative over the intermediate temperature range of 500 to 650 °C.

Application of a Composite Model in the Analysis of Creep Deformation at Low and Intermediate Temperatures

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Xinjun Yang ◽  
Xiang Ling
Keyword(s):  
Projection Method ◽  
Power Law ◽  
Creep Deformation ◽  
Primary Creep ◽  
Composite Model ◽  
Intermediate Temperature ◽  
Model Parameters ◽  
Creep Life ◽  
Temperature Creep ◽  
Multiaxial Creep

The creep behaviors of TA2 and R60702 at low and intermediate temperature were presented and discussed in this paper. Experimental results indicated that an apparent threshold stress was exhibited in the creep deformation of R60702. Meanwhile, the primary creep phase was found as the main pattern in the room temperature creep behavior of TA2. Compared with the exponential law, the power law has been proved to be a proper constitutive model in the description of primary creep phase. It also showed that θ projection method had its significant advantage in the evaluation of accelerated creep stage. Thus, a composite model which combined power law with θ projection method was applied in the creep curves evaluation at low and intermediate temperature. Based on the multiaxial creep deformation results, the model was modified and discussed. A linear relationship existed between composite model parameters and applied load. Finally, the creep life of TA2 and R60702 could be accurately predicted by the composite model, and it is suitable for the application in low and intermediate temperature creep life analysis.

High Temperature Creep Behavior and Effects of Stacking Fault Energy in Mg-Y and Mg-Y-Zn Dilute Solid Solution Alloys

2014 ◽  
Vol 783-786 ◽  
pp. 491-496
Author(s):  
Mayumi Suzuki ◽  
Yasuyuki Murata ◽  
Kyosuke Yoshimi
Keyword(s):  
Activation Energy ◽  
Solid Solution ◽  
Creep Behavior ◽  
Ternary Alloys ◽  
Dislocation Creep ◽  
Prismatic Slip ◽  
Dislocation Slip ◽  
Self Diffusion ◽  
Controlling Mechanism ◽  
Hot Rolled

Compressive creep behavior of hot-rolled (40%) Mg-Y binary and Mg-Y-Zn ternary dilute solid solution alloys are investigated in this study. Creep strength is substantially improved by the addition of zinc. Activation Energy for creep in Mg-Y and Mg-Y-Zn alloys are around 200 kJ/mol at the temperature range from 480 to 570 K. These values are higher than the activation energy for self-diffusion coefficient in magnesium (135 kJ/mol). Many stacking faults, which are planar type defects are observed on the basal planes of the magnesium matrix in Mg-Y-Zn ternary alloys. TEM observation has been revealed that the non-basal a-dislocation slip is significantly activated by these alloys. The rate controlling mechanism of Mg-Y and Mg-Y-Zn dilute alloys are considered to the cross-slip or prismatic-slip controlled dislocation creep with high activation energy for creep, more than 1.5 times higher than the activation energy for creep controlled dislocation climb.

Results From Demineralized Bone Creep Tests Suggest That Collagen Is Responsible for the Creep Behavior of Bone

1999 ◽  
Vol 121 (2) ◽  
pp. 253-258 ◽  
Author(s):  
S. M. Bowman ◽  
L. J. Gibson ◽  
W. C. Hayes ◽  
T. A. McMahon
Keyword(s):  
Trabecular Bone ◽  
Cortical Bone ◽  
Power Law ◽  
Creep Behavior ◽  
Damage Accumulation ◽  
Activation Energies ◽  
Analysis Of Covariance ◽  
Type I ◽  
Creep Tests ◽  
Demineralized Bone

Cortical and trabecular bone have similar creep behaviors that have been described by power-law relationships, with increases in temperature resulting in faster creep damage accumulation according to the usual Arrhenius (damage rate ~ exp (−Temp.−1)) relationship. In an attempt to determine the phase (collagen or hydroxyapatite) responsible for these similar creep behaviors, we investigated the creep behavior of demineralized cortical bone, recognizing that the organic (i.e., demineralized) matrix of both cortical and trabecular bone is composed primarily of type I collagen. We prepared waisted specimens of bovine cortical bone and demineralized them according to an established protocol. Creep tests were conducted on 18 specimens at various normalized stresses σ/E0 and temperatures using a noninvasive optical technique to measure strain. Denaturation tests were also conducted to investigate the effect of temperature on the structure of demineralized bone. The creep behavior was characterized by the three classical stages of decreasing, constant, and increasing creep rates at all applied normalized stresses and temperatures. Strong (r2 > 0.79) and significant (p < 0.01) power-law relationships were found between the damage accumulation parameters (steady-state creep rate dε/dt and time-to-failure tf) and the applied normalized stress σ/E0. The creep behavior was also a function of temperature, following an Arrhenius creep relationship with an activation energy Q = 113 kJ/mole, within the range of activation energies for cortical (44 kJ/ mole) and trabecular (136 kJ/mole) bone. The denaturation behavior was characterized by axial shrinkage at temperatures greater than approximately 56°C. Lastly, an analysis of covariance (ANCOVA) of our demineralized cortical bone regressions with those found in the literature for cortical and trabecular bone indicates that all three tissues creep with the same power-law exponents. These similar creep activation energies and exponents suggest that collagen is the phase responsible for creep in bone.

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