Liquid metal penetration at grain boundaries: Characterization by synchrotron radiation micro-radiography and micro-fluorescence

Forging of different steel grades is called Damascus technique and results in a layered composite material termed “Damascus steel”, but forging of different copper alloys is termed “mokume gane”. In this paper the joining of copper and iron plates by forging is described. Metallographic investigations showed well bonded interfaces of copper and iron. A very small diffusion zone was observed. To study the diffusion between copper and iron two heat treatments were performed in Ar atmosphere. After 30 minutes at 1000 °C a marginal Cu-Fe interaction took place. Above the melting point of Cu at 1100 °C an intense Cu-Fe interaction was observed, which significantly changes the interface of both metals. Cu penetrated Fe along the grain boundaries and Fe droplets were formed sporadically. This correlates with the typical morphologies of liquid metal embrittlement (LME). Moreover, Fe is dissolved in Cu at 1100 °C and after cooling fine Fe precipitates in the Cu phase were detected.

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

Metallurgical and Materials Transactions A ◽

10.1007/s11661-020-05857-3 ◽

2020 ◽

Vol 51 (8) ◽

pp. 3938-3944 ◽

Cited By ~ 2

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

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Grain Boundary Complexion Transitions

Annual Review of Materials Research ◽

10.1146/annurev-matsci-081619-114055 ◽

2020 ◽

Vol 50 (1) ◽

pp. 465-492 ◽

Cited By ~ 2

Author(s):

Patrick R. Cantwell ◽

Timofey Frolov ◽

Timothy J. Rupert ◽

Amanda R. Krause ◽

Christopher J. Marvel ◽

...

Keyword(s):

Liquid Metal ◽

Grain Boundary ◽

Grain Boundaries ◽

Bulk Composition ◽

Polycrystalline Metals ◽

Research Challenges ◽

Rapid Changes ◽

And Performance ◽

Property Changes ◽

Processing Properties

Grain boundaries can undergo phase-like transitions, called complexion transitions, in which their structure, composition, and properties change discontinuously as temperature, bulk composition, and other parameters are varied. Grain boundary complexion transitions can lead to rapid changes in the macroscopic properties of polycrystalline metals and ceramics and are responsible for a variety of materials phenomena as diverse as activated sintering and liquid-metal embrittlement. The property changes caused by grain boundary complexion transitions can be beneficial or detrimental. Grain boundary complexion engineering exploits beneficial complexion transitions to improve the processing, properties, and performance of materials. Here, we review the thermodynamic fundamentals of grain boundary complexion transitions, highlight the strongest experimental and computationalevidence for these transitions, clarify a number of important misconceptions, discuss the advantages of grain boundary complexion engineering, and summarize existing research challenges.

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Simultaneous X-ray radiography and diffraction topography imaging applied to silicon for defect analysis during melting and crystallization

Journal of Applied Crystallography ◽

10.1107/s1600576719013050 ◽

2019 ◽

Vol 52 (6) ◽

pp. 1312-1320 ◽

Cited By ~ 4

Author(s):

Maike Becker ◽

Gabrielle Regula ◽

Guillaume Reinhart ◽

Elodie Boller ◽

Jean-Paul Valade ◽

...

Keyword(s):

Synchrotron Radiation ◽

Grain Boundaries ◽

Growth Process ◽

Defect Formation ◽

Simultaneous Recording ◽

European Synchrotron Radiation Facility ◽

Crystal Defects ◽

Structural Defects ◽

X Ray

One of the key issues to be resolved to improve the performance of silicon solar cells is to reduce crystalline defect formation and propagation during the growth-process fabrication step. For this purpose, the generation of structural defects such as grain boundaries and dislocations in silicon must be understood and characterized. Here, in situ X-ray diffraction imaging, historically named topography, is combined with radiography imaging to analyse the development of crystal defects before, during and after crystallization. Two individual indirect detector systems are implemented to record simultaneously the crystal structure (topographs) and the solid–liquid morphology evolution (radiographs) at high temperature. This allows for a complete synchronization of the images and for an increased image acquisition rate compared with previous studies that used X-ray sensitive films to record the topographs. The experiments are performed with X-ray synchrotron radiation at beamline ID19 at the European Synchrotron Radiation Facility. In situ observations of the heating, melting, solidification and holding stages of silicon samples are presented, to demonstrate that with the upgraded setup detailed investigations of time-dependent phenomena are now possible. The motion of dislocations is recorded throughout the experiment, so that their interaction with grain boundaries and their multiplication through the activation of Frank–Read sources can be observed. Moreover, the capability to record with two camera-based detectors allows for the study of the relationship between strain distribution, twinning and nucleation events. In conclusion, the simultaneous recording of topographs and radiographs has great potential for further detailed investigations of the interaction and generation of grains and defects that influence the growth process and the final crystalline structure in silicon and other crystalline materials.

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