Enthalpies of the hcp-bcc transformation Delta H-tr and melting Delta H-m of Be were measured by anisothermal calorimetry which gave Delta H-tr = 6100 J/mol and Delta H-m = 7200 J/mol, The high value of Delta H-tr is explained by the strongly reduced c/a-axis ratio of the hcp modification. Maximum solubilities of the metallic impurities Al, Cr, Fe, Mg and Si in different Be qualities which annealed at about 800 degreesC are 0.01 mol% or less in each case. In the Al-Be-Fe system, Be(AI, Fe) is in equilibrium with AI(5)Fe(2) at 870 degreesC, The phases AlFeBe4 and Al2FeBe2.3 were not observed. The Be-C-Si system is marked by two two-phase equilibria Be2C-Si and Be2C-SiC at 900 degreesC, The phase diagram of the pseudo-ternary BeO-Li2O-SiO2 system was established on the basis of m-pile Be-BeO-Li4SiO4-Li2SiO3 compatibility studies at about 450 degreesC. The system is characterised by Li2BeSiO4 which is in equilibrium with BeO, Be2SiO4, SiO2, Li2Si2O5. Li2SiO3 and Li4SiO4 The latter phase is also in equilibrium with Li2Be2O3. (C) 2001 Elsevier Science B.V. All rights reserved. [References: 20]
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