Tailoring of the thermal expansion of Cr2(Alx,Ge1−x)C phases
2013 (English)In: Journal of the European Ceramic Society, ISSN 0955-2219, Vol. 33, no 4, 897-904 p.Article in journal (Refereed) Published
We report thermal expansion coefficients of the end members and solid-solution compounds in the Cr2(Alx,Ge1−x)C system. All samples studied were essentially phase-pure Cr2AlxGe1−xC except the Cr2GeC sample, which contained a substantial fraction of Cr5Ge3Cx. X-ray diffraction performed in the 25–800 °C temperature range shows that the in-plane thermal expansion remains essentially constant at about 14 ± 1 × 10−6 K−1 irrespective of Al content. The thermal expansion of the c axis decreases monotonically from 17 ± 1 × 10−6 K−1 for Cr2GeC to ∼12 ± 1 × 10−6 K−1 with increasing Al content. At around the Cr2(Al0.75,Ge0.25)C composition, the thermal expansion coefficients along the two directions are equal; a useful property to minimize thermal residual stresses. This study thus demonstrates that a solid-solution approach is a route for tuning a physical property like the thermal expansion. For completeness, we also include a structure description of the Cr5Ge3Cx phase, which has been reported before but is not well documented. Its space group is P63/mcm and its a and c lattice parameters are 7.14 Å and 4.88 Å, respectively. We also measured the thermal expansion coefficients of the Cr5Ge3Cx phase. They are found to be 16.3 × 10−6 K−1 and 28.4 × 10−6 K−1 along the a and c axes, respectively. Thus, the thermal expansion coefficients of Cr5Ge3Cx are highly anisotropic and considerably larger than those of the Cr2(Alx,Ge1−x)C phases.
Place, publisher, year, edition, pages
Elsevier, 2013. Vol. 33, no 4, 897-904 p.
Annealing, MAX phases, Thermal expansion, Rietveld refinement, Solid solution
Engineering and Technology
IdentifiersURN: urn:nbn:se:liu:diva-90143DOI: 10.1016/j.jeurceramsoc.2012.10.008ISI: 000314861000030OAI: oai:DiVA.org:liu-90143DiVA: diva2:612141
Funding Agencies|Swedish Research Council (VR) Linnaeus LiLi-NFM Strong Research Environment||2013-03-202013-03-202015-01-13Bibliographically approved