Lattice defects underneath hydrogen-induced intergranular fracture surface of Ni-Cr alloy evaluated by low-energy positron beam

Investigations of Surface Dissolution on Fatigue Crack Nucleation in Ni - 22 Cr - 2 Fe Alloy

Ni-Cr-Fe alloy specimens were fatigued in a hydrochloric acid solution cell at pH 5.6 ±0.1. Results show that the number of surface slip bands forming, extending, and widening increased with the number of cycles. Results also indicated that, initially, cracks initiated as transgranular features but took on intergranular forms as the number of cycles increased.

Hydrogen-induced intergranular failure in nickel revisited

Using a combination of high-resolution scanning and transmission electron microscopy, the basic mechanisms of hydrogen-induced intergranular fracture in nickel have been revisited. Focused-ion beam machining was employed to extract samples from the fracture surface to enable the examination of the microstructure immediately beneath it. Evidence for slip on multiple slip systems was evident on t...

A statistical, physical-based, micro-mechanical model of hydrogen-induced intergranular fracture in steel

Intergranular cracking associated with hydrogen embrittlement represents a particularly severe degradation mechanism in metallic structures which can lead to sudden and unexpected catastrophic fractures. As a basis for a strategy for the prognosis of such failures, here we present a comprehensive physical-based statistical micro-mechanical model of such embrittlement which we use to quantitativ...

Evaluation of Fracture Strength of Ceramics Containing Small Surface Defects Introduced by Focused Ion Beam

The aim of this study was to clarify the effects of micro surface defects introduced by the focused ion beam (FIB) technique on the fracture strength of ceramics. Three-point bending tests on alumina-silicon carbide (Al₂O₃/SiC) ceramic composites containing crack-like surface defects introduced by FIB were carried out. A surface defect with area in the range 19 to 35 µm was introduced at the ce...

Plasma Induced Defects in GaAs Probed by a Monoenergetic Positron Beam