Hydrogen effects on the spall strength and fracture characteristics of amorphous Fe-Si-B alloy at very high strain rates

Abstract

A novel approach is suggested, using laser-induced shock wave measurements to estimate the effects of cathodic hydrogen charging on the mechanical properties and fracture characteristics of materials. This approach is applied to (1) determine the dominant mechanism of hydrogen embrittlement (HE) in an amorphous Fe 80 B 11 Si 9 alloy; and (2) estimate the effects of the high pressures involved in cathodic charging. The dynamic spall strength of an amorphous Fe 80 B 11 Si 9 alloy shocked before and after hydrogenation by a high-power laser to very high pressures (tens of giga Pascals) is measured. The dynamic spall strength of crystalline iron is measured as well for comparison. An optically recording velocity interferometer system (ORVIS) is used to measure the profile of the free surface velocity in time. The spall strength and the strain rate are calculated from the measurement of the free surface velocity as a function of time. Fracture characteristics are studied by scanning electron microscopy (SEM). The main conclusions are (1) the most reasonable mechanism of HE in the amorphous Fe-Si-B alloy is the high-pressure bubble formation; (2) the high pressures involved in cathodic hydrogen charging or laser-induced shock waves measurements may have similar effects on fracture characteristics; and (3) at very high strain rates, the spall strength is determined mainly by the interatomic bonds.

Hydrogen effects on an amorphous Fe-Si-B alloy

“…[5] Shear bands, voids, and interconnecting cracks are observed, indicating that the defects observed in Figures 2(b) and (c) D. Hydrogen Effects on the Microstructure and are not surface artifacts. Figure 2(e) presents a region from Thermal Stability the fracture surface of a sample that was charged at 150 A/ m 2 for 1 hour and intentionally fractured by applying an Hydrogen effects on the microstructure and thermal stabilexcessive bending force.…”

“…diffusion behavior of hydrogen in dilute amorphous Fe-H, Electrochemical hydrogen charging of the amorphous ribFe-Si-H, and Fe-B-H alloys, as described in detail elsebons was performed in a solution of 0.1 N H 2 SO 4 with 5 where. [4] In a recent complementary article, [5] the authors mg/L NaAsO 2 as a surface poison. This solution is often applied laser-induced shock-wave measurements to deterused as a catholyte for ferrous samples in electrochemical mine the dominant mechanism of HE in an amorphous permeation experiments, due to the ease of the cathodic Fe 80 B 11 Si 9 alloy and to estimate the effects of the high presreaction for hydrogen evolution.…”

“…[10] Since the embrittlement phenomenon has already been dischanges in microhardness following hydrogenation of amorphous Fe 70 Cr 10 P 13 C 7 and Fe 80 P 13 C 7 alloys. The absence of cussed in detail in a complementary article, [5] this section mainly presents SEM observations that were not included any detectable changes in microhardness may result from the low content of hydrogen in these materials. The low in the previous article and explains in more detail the applicability of the high-pressure bubble-formation model to the hydrogen content leads to weak interactions between internal stress fields and to occupancy of relatively large interstitial amorphous material.…”

“…On the other hand, hydropressure bubble formation for HE in amorphous Fe 80 B 11 Si 9 , as suggested elsewhere. [5] It should also be noted that the gen solubility in amorphous alloys that contain hydrideforming elements may be fairly high. For example, a hydrovalue of E aT reported herein is higher than the value of activation energy for hydrogen desorption from amorphous gen content as high as 1.0 H/M could be detected by weight measurements in amorphous Zr 69.5 Cu 12 Ni 11 Al 7.5 following Fe 79 B 14 Si 7 (21.23Ϯ0.96 kJ/mol), as calculated elsewhere [11] by applying Kissinger's equation to the endothermic peak electrochemical charging at room temperature.…”

Dynamic fracture behaviour of Fe78Si9B13 metallic glass ribbon under laser shock loading

“…It has been found that the spall phenomenon may occur in Fe 78 Si 9 B 13 ribbon as well as other Fe‐based metallic glasses by means of laser shock loading . However, this behaviour cannot be seen from the SEM observations of specimens at both die hole diameters.…”