Mechanical and Physical Properties of Cr Containing Mo₂NiB₂ Ternary Boride

Abstract

Mechanical and physical properties of Cr containing Mo₂NiB₂ ternary borides were studied for (Mo_2-XNi_1-XCr_2X)B₂ compositions. X is set to 0, 0.25, 0.50 and 0.75 corresponding to the mixing compositions about 0, 5, 10 and 15 mass%. Dense Mo₂NiB₂ ternary borides were formed from the powders of Mo, MoB, Ni and CrB by reaction boronizing sintering with transient liquid phase. As a result, crystal structure of Mo₂NiB₂ ternary boride changed from orthorhombic to tetragonal around at 15 mass% Cr. Cr containing Mo₂NiB₂ ternary borides, especially 10 and 15 mass% Cr added borides exhibit high hardness and high elastic modulus comparable to WC and TiC. Cr containing Mo₂NiB₂ ternary boride is suitable alternative materials to wear resistant hard materials such as WC.