Structural metals at extremes

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uction The topic of “materials under extreme environments” has received signiﬁcant attention recently. Materials are key building blocks for the next generation of energy technologies, where they must feature enhanced performance at extremes of mechanical stress, strain, temperature, pressure, corrosive environments, particle radiation ﬂux, and electric or magnetic ﬁelds.1 For example, using supercritical steam signiﬁcantly increases the efﬁciency of coal-ﬁred power plants, but requires 50% higher operating temperatures and roughly double the operating pressure. Transportation applications, such as cars and aircraft, need lighter-weight and higher-strength structural materials to increase fuel efﬁciency and reduce CO2 emission. For future nuclear-ﬁssion power plants, structural and cladding materials must perform at higher temperature and high dpa (displacements per atom). These increasingly extreme operating environments accelerate the aging process in materials, leading to reduced performance and eventually to failure. Structural materials in defense, aerospace, construction, and other national-infrastructure applications also fail unpredictably, often at stresses less than 10% of the theoretical limit of strength for perfect crystals. Incremental changes in current structural materials may not produce the revolutionary breakthroughs needed for future applications. Innovative basic research that elucidates the fundamentals of how materials behave in extreme environments is required. Controlling the

matter-extreme environment interactions can help researchers to develop revolutionary new materials that perform in predictable ways at stresses approaching the theoretical limit of material strength, on the order of 10% of the elastic modulus, extending lifetimes, increasing efﬁciencies, providing novel capabilities, and lowering costs.1–3 At a more fundamental level, the development of materials with a tailored response in extreme environments addresses one of the ﬁve grand challenges outlined in the recent Basic Energy Sciences Advisory Committee report4 titled “Directing Matter and Energy: Five Challenges for Science and the Imagination”: How do we design and perfect atom- and energy-efﬁcient syntheses of revolutionary new forms of matter with tailored properties? Embodied in this grand challenge are speciﬁc science issues for structural materials at extremes, such as: 䊏 How resistant to failure in extreme conditions of temperature, radiation, or environment exposure can we make a material? 䊏 How do we make hard matter that heals damage or defects? 䊏 How mechanically strong can we make materials yet keep them lightweight? The ﬁeld of “materials under extreme environments” is quite broad and may require more than one MRS Bulletin theme issue to capture the new developments. The focus of this issue is on metals, leaving out non-metals (ceramics for nuclear

Amit Misra, Los Alamos National Laboratory, New Mexico, USA; [email protected] Ludovic Thilly, Department of Physics and Mechanics of Materials, P-prime Institute, C

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