Improving the resistance to intergranular cracking and corrosion at elevated temperatures by grain-boundary-engineering-type processing

2008 ◽  
Vol 43 (11) ◽  
pp. 3908-3916 ◽  
Author(s):  
Ulrich Krupp
Keyword(s):  
Grain Boundary ◽  
Elevated Temperatures ◽  
Grain Boundary Engineering ◽  
Intergranular Cracking

Dynamic Embrittlement - Diffusion-Induced Intergranular Cracking

2006 ◽  
Vol 258-260 ◽  
pp. 192-198
Author(s):  
Ulrich Krupp
Keyword(s):  
Grain Boundary ◽  
Elevated Temperatures ◽  
Low Cycle Fatigue ◽  
Hold Time ◽  
Fatigue Loading ◽  
Damage Mechanism ◽  
Boundary Structure ◽  
Grain Boundary Engineering ◽  
Intergranular Cracking ◽  
Dynamic Embrittlement

The present paper is about dynamic embrittlement as a generic damage mechanism. It involves grain-boundary diffusion of an embrittling species at elevated temperatures under the influence of mechanical stress. The embrittling species, either coming from the material itself or from the environment, reduces the grain-boundary cohesion and, hence, causes time-dependent intergranular fracture. Evidence of the technical significance of dynamic embrittlement is given by two examples, stress-relief cracking in steels and hold-time cracking during low-cycle-fatigue loading of nickel-base superalloys. There is an obvious relationship between the grain-boundary structure and the local susceptibility to dynamic embrittlement. This was proven by mechanical experiments on bicrystals and grain-boundary-engineering-type-processed specimens.

Dynamics of grain boundary motion at the atomic level

2004 ◽  
Vol 819 ◽  
Author(s):  
K. L. Merkle ◽  
L. J. Thompson ◽  
F. Phillipp
Keyword(s):  
Grain Boundary ◽  
Elevated Temperatures ◽  
High Resolution Electron Microscopy ◽  
Collective Effects ◽  
Polycrystalline Materials ◽  
Grain Boundary Engineering ◽  
Triple Junctions ◽  
Resolution Electron ◽  
Curvature Driven ◽  
Grain Boundary Motion

AbstractGrain boundaries (GBs) in polycrystalline materials play a pivotal role in controlling their mechanical and physical behavior. High-resolution electron microscopy (HREM) was used to study thermally activated GB migration in thin films of Al and Au at elevated temperatures (T > 0.5 Tm). Grain boundary engineering via epitaxial templating allowed the manufacture of well-defined grain and interfacial geometries. These techniques enabled the observation of tilt, but also twist and general GBs at atomic resolution in-situ at high temperatures. Surface-energy driven GB migration occurred in general GBs, whereas tilt GB motion was curvature driven. Digital analysis of HREM video recordings have given considerable insight in the dynamics of GB motion at elevated temperatures. It is not surprising that the complex and diverse migration mechanisms depend on GB geometry as well as on interatomic interactions. The results provide, among others, direct evidence for collective effects by concerted atomic shuffles, ledge propagation in (113) symmetric tilt GBs, and motions of triple junctions at elevated temperatures.

scholarly journals Evaluation of Grain Boundary Network and Improvement of Intergranular Cracking Resistance in 316L Stainless Steel after Grain Boundary Engineering

Materials ◽  
2019 ◽  
Vol 12 (2) ◽  
pp. 242 ◽  
Author(s):  
Tingguang Liu ◽  
Shuang Xia ◽  
Qin Bai ◽  
Bangxin Zhou ◽  
Yonghao Lu ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Grain Boundary ◽  
Twin Boundary ◽  
316L Stainless Steel ◽  
Grain Boundary Engineering ◽  
Intergranular Cracking ◽  
Random Boundary ◽  
Intergranular Stress Corrosion ◽  
Pressurized Water ◽  
Before And After

For understanding the improvement of intergranular stress corrosion cracking (IGSCC) propagation in grain boundary engineering (GBE)-processed metals exposed to a simulated pressurized water reactor (PWR) environment, characteristics of the grain boundary network of 316L stainless steel before and after GBE were investigated and compared, including proportions both in length and in number of ∑3n boundaries, sizes, and topology of grain clusters (or twin-related domains), and connectivity of random boundaries. The term through-view random boundary path (TRBP) was proposed to evaluate the random boundary connectivity. A TRBP is a chain of end-to-end connected crack-susceptible boundaries that passes through the entire mapped microstructure. The work provides the following key findings: (I) the length fraction of ∑3n boundaries was increased to approximately 75% after GBE, but the number fraction was only approximately 50%; (II) a connected non-twin boundary network still existed in the GBE sample due to the formation of grain clusters; (III) the GBE sample exhibited a higher resistance to IGSCC; and (IV) as the twin boundary fraction increased, the number of TRBPs decreased and the normalized length of the minimum TRBP increased monotonically, leading to a higher resistance to IGSCC.

Precision grain Boundary Engineering in commercial Bi2Te2.7Se0.3 thermoelectric materials towards high performance

2021 ◽  
Author(s):  
Shuankui Li ◽  
Zhongyuan Huang ◽  
Rui Wang ◽  
Chaoqi Wang ◽  
Wenguang Zhao ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Thermoelectric Materials ◽  
High Performance ◽  
General Strategy ◽  
Grain Boundary Engineering

The strong interrelation between electrical and thermo parameters have been regarded as one of the biggest bottlenecks to obtain high-performance thermoelectric materials. Therefore, to explore a general strategy to fully...

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