| Abstrakt: |
The binary compound Cr5B3 has a tetragonal structure with the lattice constants a=5.472±0,003, c=10.098±0.006 Å, and c/a=1.845. The phase equilibria in the systems V-Cr-B, Nb-Cr-B, and Mo-Cr-B at 1400°C have been established. In the system V-Cr-B, the continuous solid solutions VB2-CrB2, V3B4-Cr3B4, and VB-CrB have been found; the compound Cr5B3 dissolves up to 20 at.% V and the compound V3B2 dissolves up to 15 at. %Cr. In the system Nb-Cr-B, the maximum solubility of Cr in the compounds NbB2 and Nb3B2 is 15 and 25 at.%, respectively. The maximum solubilities of a third component in the borides of the system Mo-Cr-B are: 17 at.% Mo in CrB2, 16 at.% Mo in Cr3B4, 40 at.% Mo in CrB, 48 at.% Mo in Cr5B3, 6 at.% Mo in CrB2, and 10 at.% Cr in Mo2B. In the systems V-Cr-B and Mo-Cr-B, ternary phases with CuAl2 type structures have been found (the lattice constants are a = 5.188 ±0.004, c=4.318±0.003 Å, and c/a=0.832 for the composition V0,150-20Cr1.85-1.80B, and a=5.215-5.245±0.003 and c=4.352-4.383±0.003Å for Mo0.24-0.39Cr1.76-1.61 B). The ternary phase (Mo, Cr)3B2 has a U3Si2 type structure (29–40 at.% Mo, 31-20 at. %Cr, 40 at.% B;'a=5.825-5.774±0.003 and c=3.115-3.082±0.002 Å). |
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