Heterostructured Lamella Structure Unites Ultrafine-Grain Strength with Coarse-Grain Ductility

2021 ◽  
pp. 73-88
Author(s):  
Xiaolei Wu ◽  
Muxin Yang ◽  
Fuping Yuan ◽  
Guilin Wu ◽  
Yujie Wei ◽  
...  
Keyword(s):  
Ultrafine Grain ◽  
Coarse Grain ◽  
Lamella Structure

scholarly journals Heterogeneous lamella structure unites ultrafine-grain strength with coarse-grain ductility

2015 ◽  
Vol 112 (47) ◽  
pp. 14501-14505 ◽  
Author(s):  
Xiaolei Wu ◽  
Muxin Yang ◽  
Fuping Yuan ◽  
Guilin Wu ◽  
Yujie Wei ◽  
...  
Keyword(s):  
Large Scale ◽  
Low Cost ◽  
High Strength ◽  
Back Stress ◽  
Coarse Grained ◽  
Ultrafine Grain ◽  
Asymmetric Rolling ◽  
Dislocation Hardening ◽  
Ultrafine Grained ◽  
Lamella Structure

Grain refinement can make conventional metals several times stronger, but this comes at dramatic loss of ductility. Here we report a heterogeneous lamella structure in Ti produced by asymmetric rolling and partial recrystallization that can produce an unprecedented property combination: as strong as ultrafine-grained metal and at the same time as ductile as conventional coarse-grained metal. It also has higher strain hardening than coarse-grained Ti, which was hitherto believed impossible. The heterogeneous lamella structure is characterized with soft micrograined lamellae embedded in hard ultrafine-grained lamella matrix. The unusual high strength is obtained with the assistance of high back stress developed from heterogeneous yielding, whereas the high ductility is attributed to back-stress hardening and dislocation hardening. The process discovered here is amenable to large-scale industrial production at low cost, and might be applicable to other metal systems.

Extra strengthening and strain hardening in coarse-grain/ultrafine-grain laminates

2020 ◽  
Vol 272 ◽  
pp. 127858
Author(s):  
Xiang Chen ◽  
Shuaishuai Liu ◽  
Ke Liu ◽  
Guangsheng Huang ◽  
Junlei Zhang ◽  
...  
Keyword(s):  
Strain Hardening ◽  
Ultrafine Grain ◽  
Coarse Grain

scholarly journals Improvement of structural efficiency in metals by the control of topological arrangements in ultrafine and coarse grains

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Abdallah Shokry ◽  
Aylin Ahadi ◽  
Per Ståhle ◽  
Dmytro Orlov
Keyword(s):  
Plastic Instability ◽  
Ultrafine Grain ◽  
Coarse Grain ◽  
Random Structure ◽  
Heterogeneous Structure ◽  
Efficient Design ◽  
Structural Efficiency ◽  
Coarse Grains ◽  
Dimensional Finite Element ◽  
Scale Levels

AbstractImprovement of structural efficiency in various materials is critically important for sustainable society development and the efficient use of natural resources. Recently, a lot of attention in science and engineering has been attracted to heterogeneous-structure materials because of high structural efficiency. However, strategies for the efficient design of heterogenous structures are still in their infancy therefore demanding extensive exploration. In this work, two-dimensional finite-element models for pure nickel with bimodal distributions of grain sizes having ‘harmonic’ and ‘random’ spatial topological arrangements of coarse and ultrafine-grain areas are developed. The bimodal random-structure material shows heterogeneities in stress–strain distributions at all scale levels developing immediately upon loading, which leads to developing concentrations of strain and premature global plastic instability. The bimodal harmonic-structure material demonstrates strength and ductility significantly exceeding those in the bimodal random-structure as well as expectations from a rule of mixtures. The strain hardening rates also significantly exceed those in homogeneous materials while being primarily controlled by coarse-grain phase at the early, by ultrafine-grain at the later and by their compatible straining at the intermediate stages of loading. The study emphasises the importance of topological ultrafine-/coarse-grain distributions, and the continuity of the ultrafine-grain skeleton in particular.

A comparative study on the microstructure and mechanical behavior of titanium: Ultrafine grain vs. coarse grain

2016 ◽  
Vol 669 ◽  
pp. 226-245 ◽  
Author(s):  
Xiangyu Sun ◽  
Yazhou Guo ◽  
Qiuming Wei ◽  
Yulong Li ◽  
Shuangyin Zhang
Keyword(s):  
Comparative Study ◽  
Mechanical Behavior ◽  
Ultrafine Grain ◽  
Coarse Grain

Shearing Patterns of AZ31 Mg Alloy Processed by Equal-Channel Angular Pressing via Various Route

2011 ◽  
Vol 682 ◽  
pp. 33-39 ◽  
Author(s):  
Xiao Ming Feng ◽  
Tao Tao Ai
Keyword(s):  
Equal Channel Angular Pressing ◽  
Mg Alloys ◽  
Structure Evolution ◽  
Ultrafine Grain ◽  
Coarse Grain ◽  
Processing Route ◽  
Angular Range ◽  
Ecap Processing ◽  
Angular Pressing ◽  
Az31 Mg Alloy

Equal-channel angular pressing (ECAP) is used to convert coarse grain into ultrafine grain (UFG). The characteristics of ECAP and the shearing patterns obtained when ECAP applied to metals are investigated. Then propose a series of procedures to verify the structure evolution of AZ31 Mg alloys after ECAP processing. The results indicate that parameters including route, die angular and pressing passes influence on the microstructure of the AZ31 Mg alloys. Route BC is the optimum processing route due to the largest slipping angular range.

Yielding and fracture behaviors of coarse-grain/ultrafine-grain heterogeneous-structured copper with transitional interface

2019 ◽  
Vol 29 (3) ◽  
pp. 588-594 ◽  
Author(s):  
Yan-fei WANG ◽  
Ming-sai WANG ◽  
Kun YIN ◽  
Ai-hui HUANG ◽  
Yu-sheng LI ◽  
...  
Keyword(s):  
Ultrafine Grain ◽  
Coarse Grain ◽  
Fracture Behaviors

Transition of Crack Propagation Path Under Varied Levels of Load in Bimodal Grain Size Al-Mg Alloy

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Leila Ladani ◽  
Steven Nelson
Keyword(s):  
Grain Size ◽  
Crack Propagation ◽  
Crack Nucleation ◽  
Crack Propagation Rate ◽  
Propagation Path ◽  
Ultrafine Grain ◽  
Coarse Grain ◽  
Fatigue Crack Nucleation ◽  
Coarse Grains ◽  
Bimodal Grain Size

Mechanical fatigue crack nucleation and propagation is modeled in bimodal grain size aluminum alloy. A multiscale modeling approach in conjunction with a continuum based damage modeling technique, successive initiation, is used to determine microstructural site of crack nucleation and its propagation through different regions of the materials. Analyses conducted for material with different coarse grain volume ratios under different load amplitudes showed that damage initiates at the interface of coarse grains and the ultrafine grain matrix. It propagates initially through coarse grains with higher initial damage rate. Once the coarse grains lose their load bearing capacity, the load is transferred to the ultrafine matrix and it fails rather quickly. Comparison between different large grain volume ratios shows that the small distance between large grains at high coarse grain volume ratios facilitates crack bridging between coarse grains and results in very high crack propagation rate in coarse grains which eventually results in catastrophic failure of the whole structure.

scholarly journals ELECTROCHEMISTRY STUDY ON THE RELATIONSHIP BETWEEN GRAIN BOUNDARY STATE AND CORROSION BEHAVIOR OF ULTRAFINE GRAINED IRON CHROMIUM ALLOY

2020 ◽  
Vol 21 (1) ◽  
pp. 41
Author(s):  
Ahadi Damar Prasetya ◽  
Muhammad Rifai ◽  
Ahmad Hasan As'ari ◽  
Mujamilah Mujamilah ◽  
Hiroyuki Miyamoto
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Behavior ◽  
Grain Structure ◽  
Ultrafine Grain ◽  
Coarse Grain ◽  
Chromium Alloy ◽  
Boundary State ◽  
Ultrafine Grained ◽  
Ultrafine Grain Structure ◽  
Iron Chromium

ELECTROCHEMISTRY STUDY ON THE RELATIONSHIP BETWEEN GRAIN BOUNDARY STATE AND CORROSION BEHAVIOR OF ULTRAFINE GRAINED IRON CHROMIUM ALLOY. Research on stainless steel corrosion resistance continues to grow today. This reality cannot be separated from the needs of stainless steels in various fields, one of which is bio-implant. In this research, the effect of grain size on the corrosion behavior of iron-chromium (Fe-Cr) alloy was investigated. Coarse grain Fe-Cr alloy was first processed with equal channel angular pressing (ECAP) for eight cycles to obtain ultrafine grain structure. The coarse and ultrafine grain samples then were then tested using XRD, SEM-EBSD, and the pitting corrosion properties tested using potentiodynamic polarization method in NaCl 1 M solution. The result of XRD dan SEM-EBSD shows that the initial sample is truly has a coarse grain structure, while ECAP produces an ultrafine grain structure. Corrosion test results showed that the ultrafine grain sample had better pitting corrosion resistance compared to the coarse grain sample. This behavior is related to the rate of passivation that depends on non-equilibrium grain boundaries, which can be easily observed in the ultrafine grain structure. Based on these results, it can be concluded that the ultrafine grain Fe-Cr alloy has a better corrosion resistance compared to the coarse grain.

Intergranular Corrosion of Ultrafine Grain Copper Fabricated by ECAP

2007 ◽  
Vol 561-565 ◽  
pp. 2385-2388 ◽  
Author(s):  
Hiroyuki Miyamoto ◽  
Takura Mimaki ◽  
Alexei Vinogradov ◽  
Satoshi Hashimoto
Keyword(s):  
Grain Boundaries ◽  
Corrosion Damage ◽  
Corrosion Current ◽  
Ultrafine Grain ◽  
Coarse Grain ◽  
Copper Corrosion ◽  
Angular Pressing ◽  
Fine Grain ◽  
Selective Corrosion ◽  
Kinetics Of

Corrosion of ultra-fine grain (UFG) copper fabricated by equal-channel angular pressing (ECAP) has been investigated in comparison with that of recrystallized coarse grain (CG) copper. Corrosion current was estimated by a Tafel extrapolation method to examine the kinetics of corrosion in a modified Livingstone etchant, which attack dislocations and grain boundaries preferentially. UFG copper have exhibited a lower corrosion current in comparison with that in its recrystallized coarse grain (CG) counterpart despite the fact that the dislocation density and total fraction of grain boundaries are much greater in UFG copper than in CG copper. Corrosion damage on its surface is macroscopically rather uniform whereas obvious attack at grain boundaries and selective corrosion of some grain interiors were observed in CG copper.

Coarse grain parallelization and acceleration of biochemical ODE simulation using GPGPU

2014 ◽  
Vol 1 ◽  
pp. 29-32
Author(s):  
Kazushige Nakamura ◽  
Kei Sumiyoshi ◽  
Noriko Hiroi ◽  
Akira Funahashi
Keyword(s):  
Coarse Grain
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