scholarly journals Dynamic recrystallization behaviour at grain boundaries and triple junctions

2015 ◽  
Vol 89 ◽  
pp. 012007 ◽  
Author(s):  
H Miura
Keyword(s):  
Dynamic Recrystallization ◽  
Grain Boundaries ◽  
Triple Junctions

Dynamic Recrystallization Behavior of GH4586 Superalloy during Hot Compression

2010 ◽  
Vol 638-642 ◽  
pp. 2357-2362 ◽  
Author(s):  
Lei Wang ◽  
Shu Ai Wang ◽  
Yang Liu ◽  
Guang Pu Zhao
Keyword(s):  
Dynamic Recrystallization ◽  
Grain Boundaries ◽  
Laser Scanning ◽  
Confocal Laser Scanning Microscope ◽  
Confocal Laser ◽  
Triple Junctions ◽  
Scanning Microscope ◽  
Large Particles ◽  
Dynamic Recrystallization Behavior ◽  
Different Strains

Compression test for GH4586 superalloy was carried out at 1273 K and 1373 K with stain from 20% to 60%. The characteristics of dynamic recrystallization were investigated by confocal laser scanning microscope, TEM and EBSD. It was found that at 1273 K dynamic recrystallization mainly took place along preexisting grain boundaries creating a necklace structure. It was confirmed by TEM observations that the first layer of the necklace structure was formed by the mechanism of bulging of preexisting grain boundaries and the following layers were nucleated at the triple junctions of former dynamic recrystallization grains. When specimens were deformed with different strains at 1373 K, dynamic recrystallization was almost completed. Our observation showed that twinning played an important role during dynamic recrystallization by promoting dynamic recrystallization grains growing. Substructures of grains were constructed by the reconfiguration of dislocations hindered at large ' particles in interior of initial grains during dynamic recovery.

Migration of grain boundaries and triple junctions in high-purity aluminum during annealing after slight cold rolling

2015 ◽  
Vol 107 ◽  
pp. 134-138 ◽  
Author(s):  
Wenhong Yin ◽  
Weiguo Wang ◽  
Xiaoying Fang ◽  
Congxiang Qin ◽  
Xiaoguang Xing
Keyword(s):  
Cold Rolling ◽  
Grain Boundaries ◽  
High Purity ◽  
Triple Junctions ◽  
High Purity Aluminum

scholarly journals Failure Mechanisms of Cu–Cu Bumps under Thermal Cycling

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5522
Author(s):  
Kai-Cheng Shie ◽  
Po-Ning Hsu ◽  
Yu-Jin Li ◽  
Dinh-Phuc Tran ◽  
Chih Chen
Keyword(s):  
Thermal Cycling ◽  
Grain Boundaries ◽  
Maximum Stress ◽  
Failure Mechanisms ◽  
Deep Understanding ◽  
Bonding Interface ◽  
Triple Junctions ◽  
Element Analysis ◽  
Resistance Change ◽  
Hybrid Joints

The failure mechanisms of Cu–Cu bumps under thermal cycling test (TCT) were investigated. The resistance change of Cu–Cu bumps in chip corners was less than 20% after 1000 thermal cycles. Many cracks were found at the center of the bonding interface, assumed to be a result of weak grain boundaries. Finite element analysis (FEA) was performed to simulate the stress distribution under thermal cycling. The results show that the maximum stress was located close to the Cu redistribution lines (RDLs). With the TiW adhesion layer between the Cu–Cu bumps and RDLs, the bonding strength was strong enough to sustain the thermal stress. Additionally, the middle of the Cu–Cu bumps was subjected to tension. Some triple junctions with zig-zag grain boundaries after TCT were observed. From the pre-existing tiny voids at the bonding interface, cracks might initiate and propagate along the weak bonding interface. In order to avoid such failures, a postannealing bonding process was adopted to completely eliminate the bonding interface of Cu–Cu bumps. This study delivers a deep understanding of the thermal cycling reliability of Cu–Cu hybrid joints.

scholarly journals Recrystallization processes, microstructure and crystallographic preferred orientation evolution in polycrystalline ice during high-temperature simple shear

2019 ◽  
Vol 13 (5) ◽  
pp. 1495-1511 ◽  
Author(s):  
Baptiste Journaux ◽  
Thomas Chauve ◽  
Maurine Montagnat ◽  
Andrea Tommasi ◽  
Fabrice Barou ◽  
...  
Keyword(s):  
High Temperature ◽  
Grain Boundary ◽  
Dynamic Recrystallization ◽  
Grain Boundaries ◽  
Simple Shear ◽  
Shear Plane ◽  
Preferred Orientation ◽  
Dislocation Slip ◽  
Crystallographic Preferred Orientation ◽  
Polycrystalline Ice

Abstract. Torsion experiments were performed in polycrystalline ice at high temperature (0.97 Tm) to reproduce the simple shear kinematics that are believed to dominate in ice streams and at the base of fast-flowing glaciers. As clearly documented more than 30 years ago, under simple shear ice develops a two-maxima c axis crystallographic preferred orientation (CPO), which evolves rapidly into a single cluster CPO with a c axis perpendicular to the shear plane. Dynamic recrystallization mechanisms that occur in both laboratory conditions and naturally deformed ice are likely candidates to explain the observed CPO evolution. In this study, we use electron backscatter diffraction (EBSD) and automatic ice texture analyzer (AITA) to characterize the mechanisms accommodating deformation, the stress and strain heterogeneities that form under torsion of an initially isotropic polycrystalline ice sample at high temperature, and the role of dynamic recrystallization in accommodating these heterogeneities. These analyses highlight an interlocking microstructure, which results from heterogeneity-driven serrated grain boundary migration, and sub-grain boundaries composed of dislocations with a [c]-component Burgers vector, indicating that strong local stress heterogeneity develops, in particular, close to grain boundaries, even at high temperature and high finite shear strain. Based on these observations, we propose that nucleation by bulging, assisted by sub-grain boundary formation and followed by grain growth, is a very likely candidate to explain the progressive disappearance of the c axis CPO cluster at low angle to the shear plane and the stability of the one normal to it. We therefore strongly support the development of new polycrystal plasticity models limiting dislocation slip on non-basal slip systems and allowing for efficient accommodation of strain incompatibilities by an association of bulging and formation of sub-grain boundaries with a significant [c] component.

To the Question of Forming Geometrically Necessary Disclinations in Triple Junctions of Grain Boundaries in Metals

2018 ◽  
Vol 82 (9) ◽  
pp. 1125-1129
Author(s):  
G. M. Poletaev ◽  
I. V. Zorya ◽  
M. D. Starostenkov ◽  
R. Yu. Rakitin
Keyword(s):  
Grain Boundaries ◽  
Triple Junctions

scholarly journals Microstructural Evidence for Grain Boundary Migration and Dynamic Recrystallization in Experimentally Deformed Forsterite Aggregates

Minerals ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 17
Author(s):  
Caroline Bollinger ◽  
Billy Nzogang ◽  
Alexandre Mussi ◽  
Jérémie Bouquerel ◽  
Dmitri Molodov ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Dynamic Recrystallization ◽  
Grain Boundaries ◽  
Driving Forces ◽  
Electron Backscatter Diffraction ◽  
Boundary Migration ◽  
Large Strains ◽  
Grain Boundary Migration ◽  
Mapping Techniques ◽  
Von Mises

Plastic deformation of peridotites in the mantle involves large strains. Orthorhombic olivine does not have enough slip systems to satisfy the von Mises criterion, leading to strong hardening when polycrystals are deformed at rather low temperatures (i.e., below 1200 °C). In this study, we focused on the recovery mechanisms involving grain boundaries and recrystallization. We investigated forsterite samples deformed at large strains at 1100 °C. The deformed microstructures were characterized by transmission electron microscopy using orientation mapping techniques (ACOM-TEM). With this technique, we increased the spatial resolution of characterization compared to standard electron backscatter diffraction (EBSD) maps to further decipher the microstructures at nanoscale. After a plastic strain of 25%, we found pervasive evidence for serrated grain and subgrain boundaries. We interpreted these microstructural features as evidence of occurrences of grain boundary migration mechanisms. Evaluating the driving forces for grain/subgrain boundary motion, we found that the surface tension driving forces were often greater than the strain energy driving force. At larger strains (40%), we found pervasive evidence for discontinuous dynamic recrystallization (dDRX), with nucleation of new grains at grain boundaries. The observations reveal that subgrain migration and grain boundary bulging contribute to the nucleation of new grains. These mechanisms are probably critical to allow peridotitic rocks to achieve large strains under a steady-state regime in the lithospheric mantle.

A Different View on Dynamic Recrystallization

2012 ◽  
Vol 715-716 ◽  
pp. 235-242 ◽  
Author(s):  
Günter Gottstein
Keyword(s):  
Grain Size ◽  
Steady State ◽  
Dynamic Recrystallization ◽  
Grain Boundaries ◽  
Experimental Results ◽  
Critical Conditions ◽  
New Approach ◽  
Theoretical Predictions

A new approach to dynamic recrystallization (DRX) is introduced. It is based on the assumption that the critical conditions for DRX and the arrest of DRX grain boundaries are related to the development of mobile subboundaries. The theoretical predictions are compared to experimental results during incipient and steady-state DRX. The grain size sensitivity of the DRX grains establishes the desired link between deformation and DRX microstructure.

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