A naturally malleable metal can be made stronger by impeding the mechanisms of plastic deformation ( reducing grain size, precipitation hardening, work hardening, etc . ), but if this is taken to an extreme, fracture becomes the more likely outcome, and the material can become brittle.
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"' Precipitation hardening "', also called "'age hardening "', is a heat treatment technique used to increase the yield strength of malleable materials, including most structural alloys of aluminium, magnesium, nickel, titanium, and some steels and stainless steels.
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Nicholson was elected to the ( US ) National Academy of Engineering in 1983, with a citation for his leadership in government / industry engineering policy, in bio-engineering, in theory of precipitation hardening in metals ( his research field in the early 1960s ), and in solar energy materials systems.