Influence of grain boundary modifier on the strength size-dependence displayed by complex-shaped nanocrystalline nickel pillars

2017 ◽  
Vol 621 ◽  
pp. 178-183 ◽  
Author(s):  
Brandon B. Seo ◽  
Junhua Gu ◽  
Zeinab Jahed ◽  
Ting Y. Tsui
Keyword(s):  
Grain Boundary ◽  
Size Dependence ◽  
Nanocrystalline Nickel

A COMPUTATIONAL STUDY ON THE DEFORMATION OF NANOCRYSTALLINE NICKEL

2009 ◽  
Vol 23 (06n07) ◽  
pp. 1517-1522
Author(s):  
JIANQIU ZHOU ◽  
SHUN LI ◽  
NAN XU
Keyword(s):  
Finite Element ◽  
Grain Boundary ◽  
Finite Element Model ◽  
Computational Study ◽  
Equivalent Plastic Strain ◽  
Element Model ◽  
Boundary Phase ◽  
Nanocrystalline Nickel ◽  
Strain And Strain Rate ◽  
Log Normal

A phase mixture based finite element model was developed and the deformation of nanocrystalline nickel was studied in this paper. Monocrystalline grain interior phase and amorphous grain boundary phase were applied in the finite element model respectively. The digital topological model, which followed the Log-normal distribution, was generated by a systematic method. The experimental strain and strain rate hardening behaviors and severe nonlinearity phenomena of nanocrystalline nickel can be predicted very well by the numerical simulation. By presenting evolution process of Mises stress and equivalent plastic strain, we found shear localization phenomenon and much faster plastic deformation in grain boundary phase. These result in the relatively lower ductility of nanocrystalline nickel compared with that of coarse-grain counterparts.

GROWTH AND LINKAGE OF CRACKS AND FORMATION OF CREEP FRACTURE PATTERN SIMULATED BY A MULTICRACK GROWTH MODEL

Fractals ◽  
2001 ◽  
Vol 09 (02) ◽  
pp. 223-230 ◽  
Author(s):  
MANABU TANAKA ◽  
RYUICHI KATO ◽  
ATSUSHI KAYAMA
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Growth Model ◽  
Size Dependence ◽  
Grain Boundary Sliding ◽  
Fracture Pattern ◽  
Square Lattice ◽  
Creep Fracture ◽  
Lattice Effects ◽  
Boundary Sliding

A computer simulation using a multicrack growth model was carried out on the growth and linkage of cracks and the formation of creep fracture pattern resulting from the initial defects. The percolated crack patterns and the number of steps to percolation were examined by Monte Carlo simulation on a square lattice. Effects of stress and grain size on creep fracture process are then discussed. The stress and grain size dependence of the number of steps to percolation in the simulation was similar to that of grain-boundary sliding in the austenitic 21Cr-4Ni-9Mn heat-resisting steel, which controlled the growth of grain-boundary cracks. The fractal dimension of the percolation crack was also correlated with that of the creep fracture pattern in the 21Cr-4Ni-9Mn steel.

scholarly journals A brief overview on grain growth of bulk electrodeposited nanocrystalline nickel and nickel-iron alloys

2019 ◽  
Vol 58 (1) ◽  
pp. 98-106
Author(s):  
Haitao Ni ◽  
Jiang Zhu ◽  
Zhaodong Wang ◽  
Haiyang Lv ◽  
Yongyao Su ◽  
...  
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Grain Growth ◽  
Growth Process ◽  
Boundary Migration ◽  
Thermal Conditions ◽  
Iron Alloys ◽  
Nanocrystalline Nickel ◽  
Nickel Iron ◽  
Average Grain Size

Abstract This review focuses on grain growth behaviors and the underlying mechanisms of bulk electrodeposited nanocrystalline nickel and nickel-iron alloys. Effects of some important factors on grain growth are described. During thermal-induced grain growth process, grain boundary migration plays a key role. For similar thermal conditions, due to grain boundary mobility with solute drag, limited grain growth occurs in nanocrystalline alloys, as compared to pure metals. Nonetheless, in the case of stress-induced grain growth process, there are a variety of mechanisms in samples having various deformation histories. As an example the grain growth of nanocrystalline nickel and Ni-20%Fe alloy with nearly the same grain-size distribution and average grain size is compared in this paper. Thermal analysis indicates nanocrystalline nickel is much more prone to rapid grain growth than nanocrystalline Ni-20%Fe alloy. Nevertheless, grain growth of nanocrystalline Ni-20%Fe is found to be more pronounced than nanocrystalline nickel during rolling deformation.

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