Abstract

An eutectic alloy in the LaB6‒VB2 system was obtained by the cold crucible method. The ratio of components in the initial powder mixture was 40:60 mol. %. In the structure of the alloy, two-phase eutectic regions are observed, which are a LaB6 matrix filled with cylindrical VB2 fibers up to 2 μm in diameter or extended VB2 crystals with a complex cross-section and an equivalent diameter of up to 10‒15 μm. The Vickers hardness and the fracturetoughness were determined, and the relationship between these characteristics and the load on the indenter, the direction of load application, and the type of eutectic structure was established. The maximum value of crack resistance (8,6 MPa·m1/2) and high hardness (20,0 GPa) were recorded for an alloy with a rod eutectic structure when a 2 N indenter load was applied parallel to the crystallographic axis c VB2. The greatest hardening effect both at a load of 2 N and 30 N, expressed in a combination of high hardness (20,5 GPa at 2 N and 20,0 GPa at 30 N) and crack resistance (6,5 MPa·m1/2 at 2 N and 4,9 MPa·m1/2 at 30 N) was demonstrated by an alloy with a coarse conglomerate eutectic structure. Ill. 4. Ref. 24. Tab. 1.

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