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1 0 A D V A N C E D M A T E R I A L S & P R O C E S S E S | A P R I L 2 0 1 9 anical degradation, gather new insights on hydrogen-assisted dislocation, and develop new hydrogen-resistant mate- rials. mit.edu . TESTING | CHARACTERIZATION CAPTURING HYDROGEN EMBRITTLEMENT Hydrogen fuel holds potential for limiting global climate change because it could eventually be used in cars and planes. However, expensive and heavy high-pressure tanks are needed to con- tain it. Storing the fuel in the crystal lattice of the metal itself could be cheaper, lighter, and safer—but first the process of how hydrogen enters and leaves the metal must be better understood. Researchers at MIT, Cam- bridge, Mass., recently created a new method that allows observation of a metal surface during hydrogen pene- tration. The new imaging platform could address hydrogen transport and trapping in materials and reveal more about the role of crystallography and microstructural constituents on the em- brittlement process, say researchers. The new way of observing the embrit- tlement process as it happens may help to reveal how the embrit- tlement gets triggered, and it may suggest ways of slowing the process—or of avoiding it by designing alloys that are less vulnerable to embrittlement. The key to the new moni- toring process was to devise a way of expos- ing metal surfaces to a hydrogen environment while inside the vacuum chamber of a scanning electron microscope (SEM). The basic design of this contained sys- tem could also be used in other kinds of vacuum-based instruments to detect other properties. Creating a leak-proof system was crucial to making the pro- cess work, as the electrolyte needed to charge the metal with hydrogen can create dangerous conditions for the microscope. In their initial tests of three dif- ferent metals—two kinds of stainless steel and a titanium alloy—the re- searchers have already made some new findings. For example, they observed the formation and growth process of a nanoscale hydride phase in the most commonly used titanium alloy, at room temperature and in realtime. This method could help scientists further understand hydrogen-induced mech- Experimental SEM setup used to study the hydrogen-loading process. Scientists at Oak Ridge National Laboratory, Tenn., analyzed more than 50 years of data showing inconsistent trends about corrosion of structural alloys in molten salts and found that one factor matters most—salt purity. Typically, alloys used in high-temperature environments are high in chromium, which forms barrier layers that slow corrosion. However, these barriers are unstable in nuclear reactors and concentrating solar power plants that use molten salts for heat transfer and storage. Absent the protective barriers, alloy chromium leeches into the salt, aided by oxidizing impurities. In addition, pure salts have much lower corrosion rates than impure salts. The findings will guide future research aimed at developing resilient materials. ornl.gov. BRIEF A technician works on the TEAM 0.5 microscope, which has been upgraded with a superfast detector called the 4D Camera that can capture atomic- scale images in millionths-of-a-second increments. Courtesy of Thor Swift/ Berkeley Lab. SUPERFAST ELECTRON DETECTOR INCLUDES 4D CAMERA Improvements in electron micros- copy have opened up a new world of observation at the atomic scale. Elec- tron microscopy experiments can only use a fraction of the possible informa- tion generated as the microscope’s electron beam interacts with samples.