Just in time for the icy grip of winter: A team of researchers led by scientists from the U.S. Department of Energy Lawrence Berkeley National Laboratory (Berkeley Lab) has identified several mechanisms that make a new, cold-loving material one of the toughest metallic alloys ever.
The alloy is made of chromium, manganese, iron, cobalt and nickel, so scientists call it CrMnFeCoNi. It's exceptionally tough and strong at room temperature, which translates into excellent ductility, tensile strength, and resistance to fracture. And unlike most materials, the alloy becomes tougher and stronger the colder it gets, making it an intriguing possibility for use in cryogenic applications such as storage tanks for liquefied natural gas.
To learn its secrets, the Berkeley Lab-led team studied the alloy with transmission electron microscopy as it was subjected to strain. The images revealed several nanoscale mechanisms that activate in the alloy, one after another, which together resist the spread of damage. Among the mechanisms are bridges that form across cracks to inhibit their propagation. Such crack bridging is a common toughening mechanism in composites and ceramics but not often seen in unreinforced metals.
Their findings could guide future research aimed at designing metallic materials with unmatched damage tolerance. The research appears in the December 9, 2015, issue of the journal Nature Communications.
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