Thermal stability of metal borides and carbides

The relationships are discussed between the thermal stability of phases, their number in borides and carbides of Nb, Ta, W, Mo and the electron states of atoms in the component. It is shown that the stability of electron states governs the various stability of phases in the system. The phase composition of alloys of B with Nb and Ta is determined by the completion by electrons of p-shells of acceptor atoms of boron to stable p6 bond configurations. The greater metling point of the phase W3Si is determined by the stability and the presence of orbitals of 3d5 bond configurations of silicon acceptor atoms