Hydrogen trapping and embrittlement in high-strength Al alloys

Abstract

Ever more stringent regulations on greenhouse gas emissions from transportation motivate efforts to revisit materials used for vehicles1. High-strength aluminium alloys often used in aircrafts could help reduce the weight of automobiles, but are susceptible to environmental degradation2,3. Hydrogen ‘embrittlement’ is often indicated as the main culprit4; however, the exact mechanisms underpinning failure are not precisely known: atomic-scale analysis of H inside an alloy remains a challenge, and this prevents deploying alloy design strategies to enhance the durability of the materials. Here we performed near-atomic-scale analysis of H trapped in second-phase particles and at grain boundaries in a high-strength 7xxx Al alloy. We used these observations to guide atomistic ab initio calculations, which show that the co-segregation of alloying elements and H favours grain boundary decohesion, and the strong partitioning of H into the second-phase particles removes solute H from the matrix, hence preventing H embrittlement. Our insights further advance the mechanistic understanding of H-assisted embrittlement in Al alloys, emphasizing the role of H traps in minimizing cracking and guiding new alloy design.

Hydrogen embrittlement of twinning-induced plasticity steels: Contribution of segregation to twin boundaries

“…First-principles studies also propose that the hydrogen at Σ3 twins leads to a mild increase in the grain boundary energy [49], facilitating grain boundary decohesion and hence the critical stress to fracture the material, similar to what was previously observed for e.g. Al-alloys [50].…”

Machine Learning Sorting Method of Bauxite Based on SE-Enhanced Network

“…Bauxite, as the main raw material of alumina and metal aluminum, plays an irreplaceable role in the manufacturing fields of spacecrafts [1,2], automobiles [3,4], and so on. At the same time, due to the thermostability and wear resistance of bauxite, it has a wide range of application value in the fields of refractory [5,6], polishing powder [7], advanced grinding wheel, and so on.…”

Hydrogen delaying the formation of Guinier-Preston zones in aluminium alloys

“…Aluminium alloys are also not immune to hydrogen ingress and when hydrogen is introduced as a solute, it easily diffuses and segregates to crystalline defects [34,35]. Ab initio calculations have shown that hydrogen atoms strongly interact with vacancies in aluminium [36][37][38].…”

“…Previous studies focusing on the hydrogen/vacancy interactions in metals have shown that hydrogen decreases the formation energy of vacancy clusters containing hydrogen [33,37] and the vacancy migration energy [39]. Hydrogen may also delay the clustering of solutes and the coarsening of precipitates in some Al alloys [35,40]. Therefore, it is critical to understand how these interactions impact the kinetic and thermodynamic of precipitates in aluminium alloys (which may evolve even at room temperature) to predict microstructural evolutions and eventually to reduce the damaging effect of hydrogen.…”