Nickel base single crystal superalloys with higher volume fraction of γˊ are known to be severely susceptible to hydrogen embrittlement. Hydrogen is found to increase the slip planarity, accumulate dislocations in γ channels causing a macroscopic fracture along {001} γ/γˊ interface [1]. There is long standing enigma on the exact reason behind this γ/γˊ interfacial failure. Few theoretical...
Hydrogen as the lightest element and the smallest atom in the periodic table tends to diffuse fast with the capability to re-distribute quickly and penetrate almost all materials. Understanding the interactions of hydrogen with host materials is of great interest for many applications, from hydrogen storage and green energy applications to hydrogen embrittlement. We use atom probe tomography...
Abstract: Environmentally assisted embrittlement of high-strength Al alloys hinders their wide applications. The important role of hydrogen (H) associated with the H “embrittlement” mechanism occurs. However, the challenge of assessing the precise trapping sites of H makes the mechanisms remain ambiguous. In this presentation, I discuss the findings on H associated with specific...
Hydrogen is nowadays viewed as a key element for developing low-carbon energies, but it diffuses in metals and alloys and segregates in crystalline defects, reducing the ductility of the material. This phenomenon is well-known and called hydrogen embrittlement (HE). In this work, we aim to reduce the negative impact of hydrogen by adding boron at interfaces to improve the resistance against...
Across a wide-range of applications in materials science, there is growing interest in being able to accurately detect, locate and quantify the presence of hydrogen in the microstructures of materials. These include modern high-strength steels, Ni-alloys and Ti-alloys for aerospace and other engineering applications, broadly aiming to understand how to make components more resistant to the...
Zr alloys have been broadly used as cladding materials in fission reactors since 1950s [1, 2]. A universal degradation issue in this field is the oxidation of Zr cladding materials, which has been widely investigated in the past decades [3-5], but there is insufficient understanding of hydrogen ingress process during corrosion due to the fundamental difficulties in hydrogen detection. Atom...
In the burgeoning field of hydrogen energy, compositionally complex alloys promise unprecedented solid-state hydrogen storage applications. However, compositionally complex alloys are facing one main challenge: reducing alloy density and increasing hydrogen storage capacity. Here, we report TiMgLi-based compositionally complex alloys with ultralow alloy density and significant room-temperature...
Martensitic advanced high strength steel (MS-AHSS), specifically MS1500, is an identified steel for various applications in the automotive industry to reduce the car weight improving fuel economy without compromising structural integrity. Nevertheless, hydrogen embrittlement (HE) is an issue with MS-AHSS. The HE susceptibility is affected by a number of the steel’s characteristics including...
Scanning Kelvin Probe (SKP) techniques have now been in use for mapping hydrogen in materials for about a decade. Different from techniques such as Secondary Ion Mass Spectroscopy (SIMS) or Atom Probe Tomography (APT) they do not measure the hydrogen concentration at a certain site, but rather the local activity. In time-resolved experiments they can provide information about how much hydrogen...
While atom probe experiments to detect hydrogen are not new, special measures had to be taken to distinguish the H detected from the specimen from the contaminant unless molecular ion formation enabled identification. This is largely due to the residual hydrogen in conventional stainless steel atom probes. The distinction was mostly made by isotope, using deuterium or recently even tritium as...
So far, the most common practice for measuring H at microstructural features in APT is using the heavier isotope deuterium in combination with voltage pulses. For metals with a high evaporation field, including steels, the formation of H2+ ions is inhibited. Hence, the peak at 2 Da can solely be attributed to D, which was introduced via electrochemical or gas charging, or implantation. But...
The investigation of hydrogen in Atom Probe Tomography remains a relevant challenge. Its low mass, high diffusion coefficient, and presence as a residual gas in vacuum chambers generate multiple complications for APT investigations. Different solutions were proposed in the literature to charge our sample, such as ex-situ charging coupled with cryotransfer [1], or hydrogen charging at high...
Understanding the effects of hydrogen in materials became a pressing topic with the imminent shift towards green technologies and the adoption of hydrogen as energy carrier. It is expected that the use of hydrogen will increase in all industries, together with the need for safe transport and storage and consequently the development of new materials and technologies to cope with it. A critical...
APT analysis of polymers has been relatively limited compared to many other material systems due to sample preparation, data collection and data analysis challenges. Polymers are often beam sensitive and Focused Ion Beam (FIB) sample preparation is often avoided, leading to approaches based on spray deposition of polymer films [1] or self assembling monolayers [2] onto pre-fabricated...
The NanoSIMS is emerging as a powerful tool to study complex problems in materials science and, along with atom probe tomography, is one of the few techniques able to localise hydrogen and deuterium at microstructurally relevant length scales. The NanoSIMS is a high-resolution secondary ion mass spectrometry instrument capable of chemical mapping at <100 nm spatial resolution, detection limits...
Hydrogen as a fuel can be stored safely with high volumetric density in metals. It can, however, also cause embrittlement of metals. Understanding fundamental behavior of hydrogen at atomic scale is key to improve metal – metal hydride systems. However, currently, it is challenging to visualize hydrogen atoms. Here, we present our recent work in which we imaged for the first time hydrogen...
Understanding the behaviour of hydrogen in zirconium-based alloys is desired since these alloys are used for fuel cladding in light water nuclear reactors but are known to suffer from hydrogen pick-up and embrittlement during service, and delayed hydride cracking (DHC) during storage.
Reliably and accurately imaging hydrogen with atom probe tomography (APT) is challenging due to several...
The understanding of Zirconium (Zr) and Hydrogen (H) interactions is a topic of interest in the field of materials science. Zr is known to have a strong affinity with hydrogen, which can lead to the formation of hydrides that can affect the mechanical properties (embrittlement, cracking, etc) of the material [1]. Our studies are carried out on pure Zr analysed by laser-assisted atom probe...
We used APT to investigate Zr-based fuel cladding from boiling water reactor and cold-worked 316L tubes from pressurized water reactor operation.
We carried out voltage pulsing APT on cryo-FIBed Zr cladding (with low success rate); we report on one data set that - contrary to modelling and NanoSIMS experiments - does not show H trapping around an Zr(Fe,Cr)_2-precipitate and discuss how...
