Structure and thermal expansion of (Cr_x,V_1−x)_n+1AlC_n phases measured by X-ray diffraction

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• 作者：Joseph Halim^a ; ^b ; Patrick Chartier^c ; Tatyana Basyuk^d ; Tatyana Prikhna^d ; El&rsquo ; ad N. Caspi^e ; Michel W. Barsoum^a ; Thierry Cabioc&rsquo ; h^c ; ^{thierry.cabioch@univ-poitiers.fr" class="auth_mail" title="E-mail the corresponding author}
• 关键词：MAX phases ; Thermal expansion ; Carbides ; Solid solutions ; XRD
• 刊名：Journal of the European Ceramic Society
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：37
• 期：1
• 页码：15-21
• 全文大小：1568 K

文摘

MAX phases in the (Cr_x,V_1−x)_n+1AlC_n system were synthesized by reactive sintering or hot isostatic pressing of elemental powders at temperatures between 1400 °C and 1600 °C. For n = 1, a complete range (0 ≤ x ≤ 1) of solid solutions was found; for n = 2 and 3 the solubility ranges were 0.25 ≤ x ≤ 0.75 and 0 ≤ x ≤ 0.5, respectively. Powder X-ray diffraction revealed that the lattice parameters of all (Cr_x,V_1−x)_n+1AlC_n solid solutions followed Vegard’s law. The thermal expansion coefficients of the various compounds were determined from Rietveld refinements of X-Ray patterns obtained at temperatures between ambient and 800 °C. For the n = 1 and 3 phases the thermal expansion coefficients were almost isotropic; those for the n = 2, however, were quite anisotropic with the expansion along the a-axis being significantly larger than along the c-axis. As a general trend, vanadium rich compounds have smaller thermal expansion coefficients than their Cr-rich counterparts.