Non-monotonic lattice parameter variation with crystallite size in nanocrystalline solids

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• 作者：Gayatri Koyar Rane^a ; Udo Welzel^a ; Sai Ramudu Meka^a ; ^{s.meka@is.mpg.de} ; Eric Jan Mittemeijer^a ; ^b
• 关键词：Nanocrystalline metals ; Mechanical milling ; X-ray diffraction (XRD) ; Lattice parameter
• 刊名：Acta Materialia
• 出版年：2013
• 出版时间：July, 2013
• 年：2013
• 卷：61
• 期：12
• 页码：4524-4533
• 全文大小：1190 K

文摘

An anomalous dependence of the lattice parameter on the crystallite size of nanocrystalline ball-milled powders of metals was observed: lattice contraction followed by lattice expansion with decreasing crystallite size. These data were determined by application of detailed X-ray diffraction measurements. To this end the lattice parameters of the metals investigated - nickel, copper, iron and tungsten - were precisely determined by correcting for influences of stacking faults, in the face-centred cubic metals, as well as by correcting for instrument-related aberrations. The non-monotonic variation of the lattice constant was interpreted as the result of two competing mechanisms: interface-stress-induced contraction vs. expansion as a result of the stress field generated at the crystallite boundary due to the increased excess free volume in the crystallite boundary upon decreasing crystallite size.