Browsing by Author "Gray, V"

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    Elastic constants of oriented Ti3AlC2 and Ti3SiC2 obtained via coherent inelastic neutron scattering
    (International Conference on Neutron Scattering, 2017-07-12) Kirstein, O; Gray, V; Stampfl, APJ; Kisi, EH
    Effort has gone into understanding the properties of MAX phases and their archetypes, Ti3SiC2,and Ti3AlC2, is as these materials exhibit a desirable combination of metallic and ceramic properties [1]. Single crystal elastic constants(SEC), usually obtained using ab-initio calculations in combination with crystallographic information, indicate the materials to be isotropic [2]. While it is difficult to obtain single crystals it is possible to produce highly textured specimens. Using a method developed by Buchenau [3] allows using coherent inelastic neutron scattering to obtain an estimation of the SEC, and such an experiment was performed using the three-axis spectrometer TAIPAN at ANSTO [4]. Results for Ti3AlC2 agree with ab-initio calculations and the assumption of isotropy. For Ti3SiC2 experimental results of c44 = 402.7 GPa do not support isotropic values obtained from ab-initio calculations. Molecular dynamics simulations combined with inelastic neutron scatteringexperiments support the initial diffraction experiment and hence themicromechanical model that was used [5]. We present here a self-consistentdescription of the mechanical properties of the MAX phases Ti3SiC2and Ti3AlC2. [1] M. W. Barsoum et al. Annual Rev.Mat. Res. 41(2011); [2] M. F. Cover et al., J. Phys.Conds. Matt., 21(2009) 305403; [3] U. Buchenau, Sol. St. Comm.,Vol.32(12), 1979 ; [4] V. Gray et al.. J. Am. Ceram. Soc.1-6, 2016; [5] E.H. Kisi et al, J. of Phys.: Cond.Matter 22 (2010) 162202