Thermal Expansion of Diboride Solid Solutions
The thermal expansion of TiB2, CrB2 and W2B5 is re-investigated with a high temperature x-ray diffractometer up to 2000 K. The results are compared with published data . The thermal expansion behaviour of TiB2 is identical in both works. The extraordinary anisotropy of CrB2 is confirmed but the thermal expansion is lower in the present work. W2B5 seems to have a different thermal expansion behaviour at higher temperatures. The thermal expansion of (Ti,Cr)B2 and (Ti,W)B2 solid solutions are investigated. The thermal expansion coefficients of (Ti,Cr)B2 do not obbey the rule of mixture. Especially in the crystallographical c-direction there is a high increase of the lattice parameters with temperature compared to the expected data. For the (Ti,W)B2 solid solutions, there is a decrease of the thermal expansion at lower temperatures compared with TiB2.
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