PHASES AND TWINNING IN C2AL3B48 (BETA ALB12).
Abstract
The aluminum-boron phase described as beta-AlB12 was shown to consist of two crystallographically related, intergrown phases with the bulk stoichiometry of C2Al3B48. One phase (A) was orthorhombic with a = 12.34A, b = 12.631A and c = 5.08A and space group Cmma or C2ma. The other phase (B) was also orthorhombic with a = 6.17, b = 12.631 and c = 10.161 and space group Ammm, A222 or A2mm. Twinning was always present and occurred across both (110) faces. Occasionally, an unusual type of twinning appeared in which the a and b axes of both phases were parallel. This was interpreted as evidence of a disproportionation from a single high temperature phase. This was verified experimentally. The high temperature phase (C) was tetragonal with a = 8.82A, b = 5.09A and space group P4/nmm, P4/n or P4 sub 2/n. The transformation which is reversible was gradual and complete at about 850C. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1964
- Accession Number
- AD0601709
Entities
People
- J. Economy
- R. F. Giese Jr.
- V. I. Matkovich