Borides powders, properties

In this case, B4C also undergoes a grain size refinement which is very beneficial for the mechanical properties. In Fig. 55, a micrograph of a reacted TiC-B powder mixture is presented, which still exhibits TiB2 B2C agglomerates of the size of the initial TiC particles. Note that the average particle size of both reaction products is approximately 1 pm. Generally, this reaction can be employed for most of the transition metal boride-boron carbide composites since the borides are usually more stable than the particular carbides [92],... 

The process starts with a pressed powder mixture of one or more binary borides of M -type metals and the metals required for the constituent of the ternary phase and for the binder phase. This method enables the fabrication of tailored M -M -solid solutions in the ternary boride as well as allows the introduction of high-performance Fe- or Ni-based alloys with exceptional properties. The metal powders are usually atomized alloys but may also consist of powder blends of the particular elements of interest. In Fig. 113 [360] the reaction process is schematically summarized showing the M alloy denoted as metal . In principle, the first step is the boronization of the powder particles by boron diffusion... 

Combustion synthesis (44) is an efficient method for making a wide variety of materials such as carbides (45,46), borides (47), and nitrides (48,49) and is superior to conventional methods with respect to higher purity and more reactivity (Fig. 3a). When the SHS reaction is carried out with powders containing nonvolatile contaminants, significant amounts of these impurities remain in the product (50). The initial reactant mixtures (chemical composition, shape and size of reactant particles, and shape, size, and density of samples) and combustion conditions (composition and pressure of the environment, initial temperature of the compact, the method and intensity of combustion initiation, or additional external effects) determine the properties of synthesized materials (45-49). 

In addition to being of use as a boron nitride precursor, polyborazylene has proven to serve as a useful reagent for the formation of new composite metal-nitride/metal-boride materials that have improved properties over the individual pure phase metal boride or nitride. For example, titanium-boride/titanium-nitride composites have been made (eq 4) by dispersing titanium powder into polyborazylene... 

Tak] Takagi, K., Watanabe, T, Ando, T, Kondo, Y, Effect of Molybdenum and Carbon on the Properties of Iron Molybdenum Boride Hard Alloys , Inter. J. Powder Metallurgy, 22(2), 91-96 (1986) (Morphology, Phase Relations, Experimental, Meehan. Prop., Phys. Prop., 7)... 

Che] Chemienko, V.V., Martyukhin, I.D., Effect of Niobium, Molybdenum, and Tungsten on Some Properties of Iron-Boride Materials , Sov. Powder Metall. Met.Ceram., 19(2), 135-138 (1980) (Experimental, 5)... 

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