Effect of volume fraction of dispersed SiO2 particles on intermediate-temperature embrittlement in Cu–SiO2 polycrystals

1998 ◽  
Vol 13 (11) ◽  
pp. 3100-3105 ◽  
Author(s):  
Hiromi Miura ◽  
Taku Sakai ◽  
Günter Gottstein
Keyword(s):  
Stress Concentration ◽  
Stress Relaxation ◽  
Grain Boundary ◽  
Fracture Strain ◽  
Volume Fraction ◽  
Grain Boundary Sliding ◽  
Intermediate Temperature ◽  
Interfacial Diffusion ◽  
Fixed Temperature ◽  
Boundary Sliding

Several kinds of Cu polycrystals with dispersed SiO2 particles of different volume fractions were tensile tested at high temperatures from 473 K to 1023 K. All of the alloys showed clear intermediate-temperature embrittlement (ITE). Although the temperature of minimum elongation was almost the same in all the alloys, temperature dependence of fracture strain depended strongly on the SiO2 volume fraction: (1) At a fixed temperature, the fracture strain tended to first decrease with increase in SiO2 volume fraction, showed minimum in an alloy with certain volume fraction, and increased again with increase in volume fraction. (2) With increase in SiO2 volume fraction, the temperature range of ITE became narrower and sharper. These results were reasonably understood by considering the occurrence of stress concentration at grain-boundary particles induced by grain-boundary sliding (GBS) and occurrence of dynamic recrystallization and stress relaxation by Cu/SiO2 interfacial diffusion.

The Compressive Behaviors of the Mg-Zn-Er Alloy Containing I-Phase

2015 ◽  
Vol 1088 ◽  
pp. 227-232
Author(s):  
Ke Liu ◽  
Wen Bo Du ◽  
Zhao Hui Wang ◽  
Shu Bo Li
Keyword(s):  
High Temperature ◽  
Grain Boundary ◽  
Deformation Mechanism ◽  
Basal Plane ◽  
Volume Fraction ◽  
Cast Alloy ◽  
Grain Boundary Sliding ◽  
Moderate Temperature ◽  
Boundary Sliding ◽  
Main Deformation

The microstructure and compressive behaviors of the Mg-Zn-Er alloy reinforced by I-phase were investigated. The XRD results suggested that the as-cast alloy was composed of -Mg and I-phase. During compress test, the deformation mechanism was depended on the test temperature and strain. It indicated that basal plane slip played an important role in deformation at both low and high temperature. However, the main deformation mechanism of the as-cast alloy includes grain boundary sliding and twins forming at the strain of 20% at a moderate temperature (225oC) besides the basal plane slip. Moreover, the DRX occurred at the moderate temperature after the strain of 50%. At high temperature (more than 300oC), the cavity was present, and the volume fraction of the cavities increases with the temperature increasing. At the high temperature, the deformation mechanism of the as-cast alloy is mainly dislocation sliding and climbing.

Grain Boundary Sliding Kinetics and Stress Relaxation Phenomena in Ni Alloys

1991 ◽  
Vol 229 ◽  
Author(s):  
F. Cosandey ◽  
S. Ui ◽  
B. Cao ◽  
R. Schaller ◽  
W. Benoit
Keyword(s):  
Stress Relaxation ◽  
Internal Friction ◽  
Grain Boundary ◽  
Grain Boundary Sliding ◽  
Relaxation Phenomena ◽  
Ni Alloys ◽  
Boundary Sliding ◽  
Triple Points ◽  
Friction Measurements

AbstractInternal friction measurements have been performed on Ni-20 wt% Cr alloys containing trace additions of Ce ranging from 0 to 180 at ppm, in order to determine grain boundary sliding kinetics and associated stress relaxation phenomena. Two anelastic relaxation peaks have been observed corresponding to intrinsic grain boundary sliding between carbide precipitates and to macroscopic sliding with elastic accommodation at triple points. The effects of Ce on these grain boundary phenomena and resulting alloy ductilities are also presented.

Influence of Second Phases on the Superplasticity of Mg-Tm-Y-CeMM Alloys Containing LPSO-Phases

2016 ◽  
Vol 879 ◽  
pp. 1477-1482
Author(s):  
Pablo Pérez Zubiaur ◽  
Judith Medina ◽  
Gerardo Garcés ◽  
Paloma Adeva
Keyword(s):  
Grain Boundary ◽  
Earth Element ◽  
Volume Fraction ◽  
Grain Boundary Sliding ◽  
Metal Alloys ◽  
Lpso Phase ◽  
Transition Metal Alloys ◽  
Sliding Mechanism ◽  
Second Phases ◽  
Boundary Sliding

The effect of the nature of the second phases in extruded Mg-TM-Y-CeMM (TM refers to a transition metal) alloys reinforced by intermetallic MgRE (RE refers to a rare earth element) compounds and LPSO-phase on their superplasticity has been evaluated between 300 and 400°C at the strain rate of 10-4 s-1. The data have been compared with those of alloys containing a similar volume fraction of the LPSO-phase. The results evidence that no superplasticity below 350°C was found in the alloys containing exclusively the LPSO-phase while the alloys containing both MgRE compounds and LPSO-phase deform superplastically by grain boundary sliding from 300°C. These differences are related to the different behaviour of MgRE compounds and LPSO-phase in the course of superplastic regime. MgRE compounds assist to accommodate the deformation more easily than LPSO-phase, reducing tendency to develop cavities and extending the time for the occurrence of necking. The size and volume fraction of the respective phases are critical in order to promote enhanced superplastic behaviour. Maximum elongations are attained in the alloys combining similar volume fractions of MgRE compounds and LPSO-phase in which their size is reduced to the maximum. An increase in the particle size of the second phases, especially in the case of the LPSO-phase, hinders the grain boundary sliding mechanism in the alloys.

Grain boundary sliding and non-constancy strain during stress relaxation of pure Mg

2021 ◽  
Vol 817 ◽  
pp. 141349
Author(s):  
Anand Varma ◽  
Aditya Gokhale ◽  
Hariharan Krishnaswamy ◽  
Dilip K. Banerjee ◽  
Jayant Jain
Keyword(s):  
Stress Relaxation ◽  
Grain Boundary ◽  
Grain Boundary Sliding ◽  
Boundary Sliding

scholarly journals Strengthening ice through cyclic loading

2017 ◽  
Vol 63 (240) ◽  
pp. 663-669 ◽  
Author(s):  
DANIEL ILIESCU ◽  
ANDRII MURDZA ◽  
ERLAND M. SCHULSON ◽  
CARL E. RENSHAW
Keyword(s):  
Stress Concentration ◽  
Cyclic Loading ◽  
Flexural Strength ◽  
Grain Boundary ◽  
Fresh Water ◽  
Grain Boundary Sliding ◽  
Reversed Cyclic Loading ◽  
Induced Stress ◽  
Boundary Sliding ◽  
Reversed Cyclic

ABSTRACTNew experiments reveal that the flexural strength of fresh water, columnar-grained ice loaded normal to the columns may be increased by about a factor of two upon reversed cyclic loading at a frequency of ~0.1 Hz at stress amplitudes of 1.3–2.6 MPa. The effect is explained in terms of a reduction in deformation-induced stress concentration through the activation of grain boundary sliding, which is evident through boundary decohesion.

scholarly journals Superplasticity and Joining of Zirconia-Based Ceramics

1999 ◽  
Vol 601 ◽  
Author(s):  
F. Gutierrez-Mora ◽  
A. Dominguez-Rodriguez ◽  
M. Jimenez-Melendo ◽  
R. Chaim ◽  
G. B. Ravi ◽  
...  
Keyword(s):  
Grain Size ◽  
Steady State ◽  
Creep Rate ◽  
Grain Boundary ◽  
Volume Fraction ◽  
Grain Boundary Sliding ◽  
Steady State Creep ◽  
Volume Fractions ◽  
Zirconia Composites ◽  
Boundary Sliding

AbstractSteady-state creep and joining of alumina/zirconia composites containing alumina volume fractions of 20, 60, and 85% have been investigated between 1250 and 1350°C. Superplasticity of these compounds is controlled by grain-boundary sliding and the creep rate is a function of alumina volume fraction, not grain size. Using the principles of superplasticity, pieces of the composite have been joined by applying the stress required to achieve 5 to 10% strain to form a strong interface at temperatures as low as 1200°C

Examination of Fracture Interfaces in Silicon Nitride

1975 ◽  
Vol 33 ◽  
pp. 60-61
Author(s):  
Nancy J. Tighe
Keyword(s):  
Silicon Nitride ◽  
Grain Boundary ◽  
Crack Growth ◽  
Subcritical Crack Growth ◽  
Slow Crack Growth ◽  
Ceramic Materials ◽  
Grain Boundary Sliding ◽  
Boundary Phase ◽  
Turbine Engines ◽  
Boundary Sliding

Silicon nitride is one of the ceramic materials being considered for the components in gas turbine engines which will be exposed to temperatures of 1000 to 1400°C. Test specimens from hot-pressed billets exhibit flexural strengths of approximately 50 MN/m2 at 1000°C. However, the strength degrades rapidly to less than 20 MN/m2 at 1400°C. The strength degradition is attributed to subcritical crack growth phenomena evidenced by a stress rate dependence of the flexural strength and the stress intensity factor. This phenomena is termed slow crack growth and is associated with the onset of plastic deformation at the crack tip. Lange attributed the subcritical crack growth tb a glassy silicate grain boundary phase which decreased in viscosity with increased temperature and permitted a form of grain boundary sliding to occur.

INTERNAL FRICTION PEAKS CONNECTED WITH GRAIN BOUNDARY SLIDING IN Al

1983 ◽  
Vol 44 (C9) ◽  
pp. C9-759-C9-764
Author(s):  
E. Bonetti ◽  
A. Cavallini ◽  
E. Evangelista ◽  
P. Gondi
Keyword(s):  
Internal Friction ◽  
Grain Boundary ◽  
Grain Boundary Sliding ◽  
Boundary Sliding
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