Inverse Hall-Petch Effect of Hardness in Nanocrystalline Ta Films

2011 ◽  
Vol 378-379 ◽  
pp. 575-579 ◽  
Author(s):  
Zhen Hua Cao ◽  
Xiang Kang Meng
Keyword(s):  
Grain Size ◽  
Room Temperature ◽  
Creep Property ◽  
Atomic Diffusion ◽  
Creep Stress ◽  
Dominant Deformation Mechanism ◽  
Creep Stress Exponent ◽  
Room Temperature Creep ◽  
Feature Scale ◽  
Indentation Response

Hardness and creep property of nanocrystalline Ta films were studied by nanoindentation tests. Experimental results suggested that hardness decreases with the decrement of grain size, which exhibits an inverse Hall-Petch effect. A remarkable room temperature creep behavior of nanocrystalline Ta films was revealed during indentation response. Creep stress exponent decreases with the decrement of feature scale, such as grain size and indent displacement. Grain boundary (GB) mediated process involving atomic diffusion and the emission of dislocation at GB is believed to be the dominant deformation mechanism.

Grain Size Effect on the Creep Behavior of Monolithic MoSi2

1994 ◽  
Vol 364 ◽  
Author(s):  
C.R. Feng ◽  
K. Sadananda
Keyword(s):  
Grain Size ◽  
Size Effect ◽  
Stress Exponent ◽  
Creep Behavior ◽  
Molybdenum Disilicide ◽  
Grain Size Effect ◽  
Stress Range ◽  
Creep Stress ◽  
Creep Stress Exponent

AbstractThe grain size effect on the creep behavior of hot-pressed monolithic molybdenum disilicide was investigated at 1200°C in a 19–255 MPa stress range. The creep-stress exponent, n, increased from 1 at low stresses to 4 at high stresses. The grain size exponent, p, varied from 0, to 3.5 and to 8 depending on the grain size, the creep-stress exponent, and creep history.

Measurement of Press Creep Stress Exponent of ZM6 Alloy at Room Temperature

2007 ◽  
Vol 546-549 ◽  
pp. 509-511
Author(s):  
Ying Ying Zhong ◽  
Shu Fang Xu ◽  
Xin Ming Zhang ◽  
Tian Cai Guo ◽  
Yun Lai Deng
Keyword(s):  
Strain Rate ◽  
Linear Relationship ◽  
Stress Exponent ◽  
Room Temperature ◽  
Constant Load ◽  
Nano Indentation ◽  
Indentation Technique ◽  
Creep Stress ◽  
Creep Stress Exponent ◽  
Relationship Of

Nano-indentation technique was used to survey creep stress exponent of ZM6 (Mg-2.8Nd-0.7Zn-0.6Zr) alloy at room temperature. The results showed that average press creep stress exponent of ZM6 alloy was about 89.75, and independent of strain rate and hardness, which has been verified by linear relationship of the double logarithmic plots between strain rate ( ε& ) and hardness (H ) measured by a nano-indentation equipment with constant load of 500mN.

Room Temperature Creep Behavior and its Effect on Tensile Properties of CP-Ti

2017 ◽  
Author(s):  
Le Chang ◽  
Changyu Zhou ◽  
Xiaohua He
Keyword(s):  
Tensile Properties ◽  
Creep Strain ◽  
Creep Behavior ◽  
Room Temperature ◽  
Loading Rate ◽  
Temperature Creep ◽  
Creep Stress ◽  
Room Temperature Creep ◽  
Stress Dependent ◽  
Cp Ti

Commercial pure titanium (CP-Ti) is an attractive material, due to its good properties such as high strength, high specific work hardening ability, excellent plasticity, toughness, corrosion resistance and weld ability. It is commonly used in pressure vessels, such as heat exchangers, pumps, valves and so on. It has been reported that the room temperature creep has a great influence on the failure of titanium pressure vessel. In this paper, in order to investigate room temperature creep behavior and its effect on tensile properties of CP-Ti, both creep and tensile experiments were carried out. According to creep experiment results, CP-Ti shows strong stress dependent creep behavior at the creep stress higher than 305MPa. On the contrary, the strong loading rate dependent creep behavior occurs at the creep stress lower than 305MPa. Besides, creep strain of CP-Ti can be reduced by pretension. As pretension reaches 6%, creep behavior of CP-Ti is completely suppressed at the creep stress of 320MPa. Subsequent tensile test results show that the occurrence of room temperature creep obviously enhances the strength of CP-Ti. With the increase of creep strain and loading rate in previous creep tests, the yield strength and tensile strength of CP-Ti increase.

Room temperature creep of fine-grained pure Mg: A direct comparison between nanoindentation and uniaxial tension

2009 ◽  
Vol 24 (5) ◽  
pp. 1615-1618 ◽  
Author(s):  
C.L. Wang ◽  
T. Mukai ◽  
T.G. Nieh
Keyword(s):  
Grain Size ◽  
Stress State ◽  
Uniaxial Tension ◽  
Stress Exponent ◽  
Deformation Mechanism ◽  
Room Temperature ◽  
Apparent Stress ◽  
Fine Grained ◽  
Temperature Creep ◽  
Room Temperature Creep

Nanoindentation creep and uniaxial tension were conducted on pure Mg with a grain size of about 2 μm at room temperature and the data were directly compared. Despite the differences in stress state, the two sets of data were found to match remarkably well with each other. An apparent stress exponent value of 4 was obtained and the deformation mechanism was discussed in light of dislocation slips and twinning in anisotropic Mg.

Effect of Microstructure Size on Deformation Kinetics and Thermo-Mechanical Fatigue of 63Sn37Pb Solder Joints

1996 ◽  
Vol 118 (2) ◽  
pp. 49-54 ◽  
Author(s):  
Zhenfeng Guo ◽  
Hans Conrad
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Cooling Rate ◽  
Room Temperature ◽  
Boundary Area ◽  
Deformation Kinetics ◽  
Mechanical Fatigue ◽  
Creep Stress ◽  
Boundary Sliding ◽  
Creep Stress Exponent

An increased cooling rate following reflow produced a decrease in the microstructure size including the size of the colonies, the Pb-rich dendrites and the eutectic phases. The decrease in microstructure size gave an increased creep rate at room temperature and a decrease in the creep stress exponent. Also, thermo-mechanical fatigue crack growth rate decreased and fatigue life increased with the decrease in microstructure size. These effects of the increased cooling rate were attributed to an increase in boundary sliding which could occur from the increase in boundary area with decrease in microstructure size.

Room temperature creep behavior of nanocrystalline Gd2Zr2O7 ceramic with grain size below 10 nm

2020 ◽  
Vol 46 (18) ◽  
pp. 29321-29325
Author(s):  
Haomin Wang ◽  
Zhangyi Huang ◽  
Jirui Deng ◽  
Duanwei He ◽  
Jun Wang ◽  
...  
Keyword(s):  
Grain Size ◽  
Creep Behavior ◽  
Room Temperature ◽  
Temperature Creep ◽  
Room Temperature Creep
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