Effect of impurities on the strengthening of CaF2 single crystals

Autor: Patrick S. Nicholson, M. N. Sinha
Rok vydání: 1977
Předmět:
Zdroj: Journal of Materials Science. 12:1451-1462
ISSN: 1573-4803
0022-2461
DOI: 10.1007/bf00540862
Popis: The critical resolved shear stress (CRSS) of pure and aliovalently doped (with Y+3 and Na+) CaF2 single crystals have been measured in compression along [1 1 1] axis between room temperature and 873 K. Strain rate cycling and/or stress relaxation experiments were performed to obtain the necessary parameters for the determination of rate-controling mechanism for plastic flow. The measured temperature and concentration dependences of the activation parameters suggest that the elastic interaction of dislocations with impurity cation-lattice anion defect pairs determine the CRSS as in alkali halide crystals. The CRSS for CaF2 single crystals doped with trivalent Y+3 were found an order of magnitude larger than those doped with the monovalent Na+. Based on the valence of dopant cations and the magnitude of hardening produced, solution hardening in CaF2 could be divided into two groups: “rapid” and “gradual” hardening.
Databáze: OpenAIRE
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