Role of Random and Coincidence Site Lattice Grain Boundaries in Liquid Metal Embrittlement of Iron (FCC)-Zn Couple

2020 ◽  
Vol 51 (8) ◽  
pp. 3938-3944 ◽  
Author(s):  
M. H. Razmpoosh ◽  
A. Macwan ◽  
F. Goodwin ◽  
E. Biro ◽  
Y. Zhou
Keyword(s):  
Liquid Metal ◽  
Grain Boundaries ◽  
Coincidence Site Lattice ◽  
Liquid Metal Embrittlement ◽  
Site Lattice

On the Role of Schottky Disorder on the Stability and Structure of (100) Twist Grain Boundaries in Nio

1983 ◽  
Vol 24 ◽  
Author(s):  
D. Wolf
Keyword(s):  
Grain Boundaries ◽  
Point Defects ◽  
Coincidence Site Lattice ◽  
Unit Cell ◽  
Twist Boundary ◽  
Site Lattice ◽  
Metastable Structures ◽  
The Stability ◽  
Twist Boundaries

ABSTRACTRecent calculations on (100) coincidence-site lattice (CSL) twist boundaries in the NaCl structure have shown that without point defects these boundaries are only marginally stable. Following an earlier suggestion that point defects are the likely source for the considerable stability of these boundaries observed experimentally for Mgo and NiO, Tasker and Duffy have shown recently that the creation of a Schottky pair can, indeed, stabilize a (100) twist boundary in NiO. In this article a variety of configurations in which one or more Schottky pairs have been created in the perfect CSL or anti-CSL unit cell are investigated. It is concluded that many metastable structures may exist which differ mainly with respect to their different interfacial mass densities and the relative translation of the two halves of the bicrystal.

scholarly journals Effect of Silicon and Retained Austenite on the Liquid Metal Embrittlement Cracking Behavior of GEN3 and High-Strength Automotive Steels

2019 ◽  
Vol 98 (12) ◽  
pp. 351s-364s ◽  
Author(s):  
MURALI TUMULURU ◽  
Keyword(s):  
Liquid Metal ◽  
Grain Boundaries ◽  
Resistance Spot Welding ◽  
Retained Austenite ◽  
Spot Welding ◽  
Liquid Metal Embrittlement ◽  
Trip Effect ◽  
Cracking Behavior ◽  
Resistance Spot

GEN3 steels are a new family of automotive sheet steels developed and commercialized in the last three years, specifically for body-in-white applications. The high ductility in GEN3 steels is typically achieved through the transformation-induced plasticity (TRIP) effect by the addition of silicon or aluminum. When these steels are formed into parts, the TRIP effect of austenite to martensite transformation provides enhanced ductility. Typically, 10 to 12 micrometers of zinc coating (known as galvanized coating) is applied to automotive steel sheets for corrosion protection. Liquid metal embrittlement (LME) cracking can occur during resistance spot welding (RSW) of galvanized steels. LME cracking occurs when molten zinc penetrates prior austenite grain boundaries of the steel substrate. The precise role of silicon in the LME cracking behavior in TRIP and GEN3 steels is unknown. Therefore, a study was undertaken to examine the role of silicon in LME cracking behavior of GEN3 steels. The purpose was also to examine if the presence of retained austenite is required for LME cracking to occur. In this study, laboratory heats were prepared using three silicon levels. Samples cut from galvanized panels were welded using a resistance spot welding machine, and weld areas were examined metallographically for the presence of LME cracks. Gleeble® simulations were done to study the LME behavior of the three steels prepared. Base materials were examined with a scanning electron microscope using the electron back-scattered diffraction (EBSD) method to examine the nature of grain boundaries found. The effect of retained austenite in LME cracking was studied using the Gleeble®. Both RSW and Gleeble® results showed silicon promotes LME cracking in steels, predominantly in the weld heat-affected zones(HAZs). More low-energy, low-coincidence site lattice (CSL) boundaries were found as the silicon content of the steel was decreased. These boundaries do not host cracks. Higher silicon appeared to shrink the safe temperature range over which LME cracks could be avoided, thus indicating heat in-put control to limit cracks has limited windows as the silicon in steel goes up. It was shown that the presence of retained austenite in steel is not a prerequisite for LME cracking to occur.

The Role of a Bilayer Interfacial Phase on Liquid Metal Embrittlement

Science ◽  
2011 ◽  
Vol 333 (6050) ◽  
pp. 1730-1733 ◽  
Author(s):  
J. Luo ◽  
H. Cheng ◽  
K. M. Asl ◽  
C. J. Kiely ◽  
M. P. Harmer
Keyword(s):  
Liquid Metal ◽  
Liquid Metal Embrittlement ◽  
Interfacial Phase

A Role of Low Energy Grain Boundaries in the Abnormal Grain Growth in Fe-3%Si Alloy

2011 ◽  
Vol 127 ◽  
pp. 89-94 ◽  
Author(s):  
Ye Chao Zhu ◽  
Jiong Hui Mao ◽  
Fa Tang Tan ◽  
Xue Liang Qiao
Keyword(s):  
Grain Boundaries ◽  
Grain Growth ◽  
Electron Backscatter Diffraction ◽  
Dominant Role ◽  
Coincidence Site Lattice ◽  
Diffraction Method ◽  
Abnormal Grain Growth ◽  
Low Energy ◽  
Backscatter Diffraction

Low energy grain boundaries were considered to be important in abnormal grain growth by theoretical deduction. The disorientation angles and coincidence site lattice grain boundaries distribution of more than 20 Goss grains and their neighboring matrix grains in primary recrystallized Fe-3%Si alloy were investigated using an electron backscatter diffraction method. It was found that the frequency of low energy grain boundaries of Goss grains which are more likely to abnormally grow are higher than their neighboring matrix grains, which indicated that low energy grain boundaries play a dominant role in the abnormal grain growth of Fe-3%Si alloy. The result meets well with the abnormal grain growth theory.

The Morphology of Grain Boundary Interactions with Twins in YBa2Cu3O7−δ

1993 ◽  
Vol 319 ◽  
Author(s):  
Jenn-Yue Wang ◽  
A. H. King
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Twin Boundary ◽  
Interfacial Energy ◽  
Coincidence Site Lattice ◽  
The Other ◽  
Twin Boundaries ◽  
Site Lattice ◽  
Dislocation Arrays

AbstractVarious morphologies are observed where twins meet grain boundaries in YBa2Cu3O7−δ. Twins may be “correlated” at the boundary (i.e. twin boundaries from one grain may meet a twin boundary from the other grain in a quadruple junction) and the twins may be narrowed or “constricted” at the boundary. These effects are determined by the interfacial energy. We estimate the energy of the various interfaces by determining the dislocation arrays they contain, using the constrained coincidence site lattice (CCSL) model and Bollmann's O2-lattice formalism. Our approach indicates that there are significant changes in the energy of the interfaces and is thus able to explain the variety of observed morphologies.

Toward Realizing the Structure-Property Link in Polycrystalline Thin Films

1994 ◽  
Vol 343 ◽  
Author(s):  
C. S. Nichols
Keyword(s):  
Thin Films ◽  
Grain Boundaries ◽  
Coincidence Site Lattice ◽  
Polycrystalline Materials ◽  
Structure Property ◽  
New Approach ◽  
Site Lattice ◽  
Polycrystalline Thin Films ◽  
Structures And Properties ◽  
Polycrystalline Form

ABSTRACTMany materials for engineering applications are used in polycrystalline form and contain grain boundaries with a range of structures and properties. However, most research on grain boundaries to date has focussed exclusively on symmetric coincidence site lattice interfaces. To go beyond descriptions for these simple interfaces and thence to an aggregate of grains and grain boundaries in a polycrystal will require a new approach. Here we discuss two models for properties of polycrystalline materials, including their advantages and drawbacks, and indicate the microstructural variables available to optimize properties.

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