Effect of dislocation distribution on the yield stress in ferritic steel under identical dislocation density conditions

2020 ◽  
Vol 177 ◽  
pp. 176-180 ◽  
Author(s):  
Yuki Tanaka ◽  
Takuro Masumura ◽  
Toshihiro Tsuchiyama ◽  
Setsuo Takaki
Keyword(s):  
Dislocation Density ◽  
Yield Stress ◽  
Ferritic Steel ◽  
Dislocation Distribution

The plasticity and cleavage of polycrystalline beryllium I. Yield and flow stresses

1980 ◽  
Vol 370 (1740) ◽  
pp. 17-27 ◽  
Keyword(s):  
Grain Size ◽  
Flow Stress ◽  
Dislocation Density ◽  
Temperature Dependence ◽  
Yield Stress ◽  
Dislocation Motion ◽  
Orientation Factor ◽  
High Rigidity ◽  
Rigidity Modulus

The dependence of the yield and flow stresses of vacuum-cast and extruded polycrystalline beryllium on the grain size, d, is studied over 20-400 °C. Both follow the standard d -1/2 relationship. The Taylor orientation factor in the deformation of the poly crystal is ca. 4.3. The marked temperature dependence of the yield stress between 20 and 200 °C arises primarily from the intragranular resistance to dislocation motion, in particular on prismatic planes. The variation of the flow stress with d1/2 increases progressively with strain and this is attributed to the effect of grain size on the dislocation density at a given strain; the increase is particularly marked for beryllium because of its high rigidity modulus.

Dislocation Distribution in Graded Composition IngaAs Layers

1993 ◽  
Vol 325 ◽  
Author(s):  
S.I. Molina ◽  
G. Gutiérrez ◽  
A. Sacedón ◽  
E. Calleja ◽  
R. García
Keyword(s):  
Detection Limit ◽  
Dislocation Density ◽  
Layer Thickness ◽  
Gaas Substrate ◽  
Ingaas Layer ◽  
Constant Composition ◽  
Defect Distribution ◽  
Dislocation Distribution

The defect distribution of a graded composition InGaAs layer grown on GaAs by MBE has been characterized by TEM (XTEM, PVTEM, HREM). The observed configuration does not correspond completely with that theoretically predicted. Dislocation misfit segments are in a quantity much bigger than in constant composition layers. Dislocation density is quite uniform up to a certain layer thickness t1. Few dislocations are observed between this t1 thickness and a larger thickness t2. Dislocation density is below the detection limit of XTEM for thicknesses bigger than t2. Some dislocations are observed to penetrate in the GaAs substrate.Several mechanisms (reactions between 600 dislocations, Hagen-Strunk and modified Frank-Read processes) are proposed to explain the interactions of dislocations in the epilayer and their penetration in the substrate.

Effect of dislocation density and aging on the yield stress of Al-Cu-Mg-Mn alloys

1973 ◽  
Vol 5 (8) ◽  
pp. 956-959
Author(s):  
Yu. M. Vainblat ◽  
L. B. Ber ◽  
S. S. Khayurov
Keyword(s):  
Dislocation Density ◽  
Yield Stress

Effect of Optimization of Shot Peening Parameters on Surface Integrity of NAK80

2010 ◽  
Vol 426-427 ◽  
pp. 537-539 ◽  
Author(s):  
Hong Miao ◽  
Dun Wen Zuo ◽  
Hong Feng Wang ◽  
X.W. Sha
Keyword(s):  
Residual Stress ◽  
Plastic Deformation ◽  
Dislocation Density ◽  
Crack Initiation ◽  
Yield Stress ◽  
Surface Integrity ◽  
Shot Peening ◽  
Experimental Result ◽  
Near Surface ◽  
Crystal Block

Shot peening is known to improve the fatigue performance of materials. The improvement in fatigue is that plastic deformation in the surface increases hardness, yield stress and microstrain of thinning Crystal block and dislocation density, and formed advantaged compress residual stress that are introduced into the near-surface of the components and which hinder crack initiation and growth. But over peening effect is produced when shot peening strengthening goes beyond a certain limit, which was adverse to improve surface quality. This paper adopted the optimization of the critical peening parameters to avoid appearing over peening effect. The experimental result showed that arc high value of optimal shot peening was 0.40mm.

Defects and Electrical Properties of Crystalline Silicon at Different Metallurgical Route

2013 ◽  
Vol 420 ◽  
pp. 134-138
Author(s):  
Hui Xian Lai ◽  
Liu Qing Huang ◽  
Ming Fang ◽  
Cheng Hao Lu ◽  
Juan Chen ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Dislocation Density ◽  
Crystalline Silicon ◽  
Acid Leaching ◽  
Refining Slag ◽  
Dislocation Distribution ◽  
Vacuum Refining ◽  
Slag Treatment ◽  
Individual Grains ◽  
Dislocation Formation

To investigate the effects of the metallurgical route on the defects in mc-Si, various metallurgical routes were conducted. Dislocation formation and the resistivity of the mc-Si were also studied. The results showed that high inhomogeneity in dislocation distribution within individual grains and paralleled tacking faults could be observed when the ingot was grown by using the feedstock prepared by adopting the sequence of slag treatment, acid leaching and vacuum refining. Different grains have various dislocation density, which was showed in ingot grown by utilizing the feedstock prepared by adopting the sequence of vacuum refining, slag treatment and acid leaching, tacking faults could also be seen, as well as some dislocation clusters. The resistivity of this two ingots was detected at various height by using the a 4-point probe silicon tester, it was expected that the resistivity of these two ingots has the same tendency of the change, and the value of the resistivity of the ingot obtained using the previous technology was relatively higher than that of the ingot obtained using the latter technology.

Dislocations and Plasticity in Silicon Crystals by 3-D Mesoscopic Simulations

1998 ◽  
Vol 538 ◽  
Author(s):  
L.P. Kubin ◽  
A. Moulin ◽  
P. Pirouz
Keyword(s):  
Dislocation Density ◽  
Yield Stress ◽  
Low Temperatures ◽  
Mechanical Twinning ◽  
Mesoscopic Simulation ◽  
Brittle To Ductile Transition ◽  
Silicon Crystals ◽  
Partial Dislocations ◽  
Yield Point Phenomenon ◽  
Dislocation Sources

AbstractSeveral problems related to the dynamics of dislocation sources and the plasticity of silicon crystals are investigated with the help of a mesoscopic simulation. The questions successively examined are the dynamics of a source of perfect dislocations and the conditions under which perfect or partial dislocations are emitted by a source. This leads to a discussion of the initial steps of the model proposed by Pirouz for mechanical twinning and, further, to the suggestion that a relation may exist between several transitions experimentally observed at low temperatures in elemental or compound semi-conductors: a change in the slope of the yield stress vs. temperature curves, a brittle-to-ductile transition and a change in the nature of the mobile dislocations. Finally, simulations are presented of the yield point phenomenon that is a well-known feature of Si and Ge crystals. The results are discussed in terms of evolutionary laws for the total dislocation density during straining.

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