The synthesis of Ti3SiC2 by pressureless reactive sintering of Ti/SiC/C mixtures under an Ar atmosphere has been studied using in situ neutron diffraction. The intermediate phases TiCx and Ti5Si3Cx (x≤ 1) form first at ∼800–1400°C. These phases are consumed in the formation of Ti3SiC2, at ∼1500°C. After sintering, Ti5Si3Cx disappears but an amount of TiCx remains in the sample primarily as a surface layer. The studies appear to support a suggestion that the intermediate phases react to form Ti3SiC2 through a diffusion‐controlled process. Prolonged stepwise heating under argon in some experiments resulted in decomposition of Ti3SiC2 above ∼1400°C and significant disproportionation of the sample.
The reactive sintering of 3Ti/SiC/C to form the layered ternary carbide Ti3SiC2 was studied in situ by time‐resolved neutron powder diffraction. A number of intermediate processes occur during the synthesis beginning with the α‐β transition in Ti. Concurrent with the α‐β transition, two intermediate phases, TiCx and Ti5Si3Cx (x≤ 1), form. These phases account for almost the entire sample in the range 1500–1600°C beyond which they react with each other and a small amount of free C to form the product phase Ti3SiC2.
In paper I [Wu et al. (1998). J. Appl. Cryst. 31,[356][357][358][359][360][361][362] an approach was developed to the problem of modelling dislocation-induced X-ray or neutron-diffraction-line broadening. This paper applies those findings to the Rietveld refinement of the neutron powder diffraction profiles of deuterium-cycled LaNi5 and/%PdD0.66. These interstitially modified materials exhibit, respectively, strong and weak anisotropic strain broadening. The broadening in LaNi5 is consistent with a dislocation slip system a/3 (2110) {0]-10}, in agreement with transmission electron microscopy studies. In PdD0.66 the model predicts a regular distribution of screw dislocations, which remains to be confirmed by other techniques.
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