Abstract
In 1989, fueled by his prior reports and findings, Prof. Herbert Gleiter published a seminal work on the synthesis, processing, and possibilities for nanocrystalline materials. This spark exploded into the field of bulk nanocrystalline metals by severe plastic deformation processing, with the primary driver being attaining the ultimate strength of a metal through refinement of the grain sizes to a level approaching the theoretically possible limits. This paper will briefly explore the historical development of SPD and based on Turnbull’s strategy of “energizing and quenching” materials to attain a desirable metastable state, present thoughts on incipient-related areas of exploration, including thermal stabilization through solute additions, the role of trace impurities and interstitials, the smallest grain size achievable (both theoretically and practically), and the captivating yet hazy character and role of the grain boundary. Lastly, some new approaches to making and then controlling the behavior of nanocrystalline materials will be presented. At each stage, opportunities for future study will be raised. On the 50th Anniversary of Metallurgical and Materials Transactions A, it is hoped that this report will build off the seed planted by Gleiter and inspire new work and collaborations in the years to come.
Highlights
THE rote history of ‘‘nanotechnology’’ is frequently initiated through a discussion of the pseudo-prophetic lecture of Prof
Ziman recognized that crystalline defects and dislocations, and impurities would disturb the pristine order of a crystal, yet noted that ‘‘Such imperfections give rise to many interesting physical phenomena, but we shall ignore them, except incidentally, in the present discussion.’’ Gleiter’s lecture and his subsequent works employed the opportunity to uniquely explore the ignored ‘‘interesting physical phenomena’’ in grain boundaries as the crystal size decreases to nanometer length scales, and ignited the imaginations of the broad materials science community.[4]
The disorder prescribed at the grain boundary of nanocrystalline material was stated by Gleiter to be atomically periodic in nature and fundamentally different from the parent crystal lattice
Summary
THE rote history of ‘‘nanotechnology’’ is frequently initiated through a discussion of the pseudo-prophetic lecture of Prof. This is yet another foundational and rousing Metallurgical Transactions A paper[27] presented by Campbell for the 1980 Edward DeMille Campbell Memorial Lecture He identified some prescient ‘‘Problems and Opportunities in Metastable Structure and Synthesis,’’ including impurity trapping in crystals, superheating in laser pulsing, compositionally modulated films for atomic transport, and dispersion by plastic deformation to explore both the limit of interfacial densities and dislocation content, and dislocation core properties. Starting with the mechanical milling approach discussed by Gleiter,[7] an unending number of processing approaches to ‘‘energize and quench’’ metallic materials have been developed with the goal of refining grain sizes to the nanoscale while lending them high-angle grain boundaries, some modicum of stability and, primarily, increased strength An early conjectured model of nanocrystallization (largely for high-stacking fault energy fcc materials) during high-energy milling (intense cyclic deformation at highstrain rates) was summarized into three stages by Fecht
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
