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Metals: hydrogen probe divides nickel into grains Identifying all hydrogen absorption sites at metallic grain boundaries allows for a quantitative prediction of metal failure. An international team of researchers led by Ting Zhu at Georgia Institute of Technology developed a method to geometrically divide nickel metal into polyhedral packing units of atoms by embedding hydrogen atoms into the nickel atomic lattice. By using atomistic simulations to examine the boundaries through these atomic packing units, they showed that hydrogen binds to nickel via an electronic effect and that grain boundary failure due to hydrogen worsens at higher temperatures. Reducing grain boundary strength therefore depended on the location of hydrogen embedded in nickel as well as hydrogen concentration at the grain boundaries. Establishing a framework to quantify metal failure due to hydrogen absorption may help up mitigate failure in hydrogen-containing pressurized vessels and pipelines.