Similarities and Differences in Mechanical Alloying Processes of V-Si-B and Mo-Si-B Powders

Abstract

V-Si-B and Mo-Si-B alloys are currently the focus of materials research due to their excellent high temperature capabilities. To optimize the mechanical alloying (MA) process for these materials, we compare microstructures, morphology and particles size as well as hardness evolution during the milling process for the model alloys V-9Si-13B and Mo-9Si-8B. A variation of the rotational speed of the planetary ball mill and the type of grinding materials is therefore investigated. These modifications result in different impact energies during ball-powder-wall collisions, which are quantitatively described in this comparative study. Processing with tungsten carbide vials and balls provides slightly improved impact energies compared to vials and balls made of steel. However, contamination of the mechanically alloyed powders with flaked particles of tungsten carbide is unavoidable. In the case of using steel grinding materials, Fe contaminations are also detectable, which are solved in the V and Mo solid solution phases, respectively. Typical mechanisms that occur during the MA process such as fracturing and comminution are analyzed using the comminution rate K P . In both alloys, the welding processes are more pronounced compared to the fracturing processes.

Effect of Initial Powders on Properties of FeAlSi Intermetallics

“…Increase in hardness and the saturation on the constant value during mechanical alloying is generally observed [27,28]. The hardening rate depends on the kinetic energy of the collisions which can be driven by the milling parameters such as rotational speed, powder to ball ratio (material of the balls), etc.…”

“…The hardening rate depends on the kinetic energy of the collisions which can be driven by the milling parameters such as rotational speed, powder to ball ratio (material of the balls), etc. The lower rotational speed or lighter balls cause slower increase in hardness and require more time for the completion of the MA process [27]. The increase in hardness of the MA powders can be caused by different mechanisms.…”

Coating Reactions on Vanadium and V-Si-B Alloys during Powder Pack-Cementation

“…Therefore, a coating will be necessary to survive harsh operation conditions of aggressive environments without degradation in order to realize any benefits from V addition to Mo-Si-B alloys, but also for newly developed V-Si-B alloys [ 3 , 5 , 14 , 15 , 16 ].…”

Preparation of Spherical Mo5Si3 Powder by Inductively Coupled Thermal Plasma Treatment

“…Hence, powder metallurgy processes are an attractive way to fabricate components of Mo silicide-based alloys. Previous studies have attempted to fabricate Mo silicide-based alloys [14,15] and Mo silicide powders [16] by mechanical alloying. However, powders fabricated by mechanical alloying suffer from low productivity and oxygen contamination, as well as an irregular morphology.…”