Papers by Keyword: Powder Mixture

Abstract: The influence of basic high-temperature synthesis parameters on the process of structure formation in the mechanically activated powder mixture 3Ti+Al was investigated in the study. The synthesis was realized by the method of induction heating in the thermal explosion mode. The heating temperature of the mixture reached 1500°C during the solid state reaction. This temperature exceeded the adiabatic combustion temperature. The investigations of the phase structure formation processes were conducted by XRD methods. In order to obtain a Ti₃Al single-phase compound, the optimal time-temperature parameters of the synthesis were determined.

Abstract: Selective laser melting (SLM) is an advanced manufacturing technology, which is flexible in building three-dimensional (3D) metallic parts. In this work, SLM experiment of a multicomponent Ni-based composite powder, which consisted of Ni, Cr, Fe, and Al powders, was conducted with favorable forming ability. The SEM, EDX, and XRD analysis were used to characterize the surface morphology, microstructure, and phase structure of as-formed Ni-based alloy. The XRD analysis showed that the as-received phase structure was Ni based solid solution. The SEM analysis of surface morphology revealed that metal agglomerates or balls were very easily formed in SLM surface, between which some pore channels existed. The surface condition and porosity could be improved by increasing laser energy input, because of a higher molten temperature and accordingly better flowing and flatting characteristics. The SEM analysis of microstructure showed that the crystalline grains were in cellular and columnar shape. Moreover, the grains were very fine with average dimensions about 5μm, due to the rapid cooling rate with rapid laser beam moving. The EDX analysis illustrated that the element contents of starting powder were uniformly distributed in as-prepared sample. A case investigation into SLM of this composite powder to form an impeller was also performed.

Abstract: Powder forging is used for heavy-loaded parts (rings of rolling-contact bearings, gears etc.) production. Rolling contact fatigue is material property values of which characterize possibility of practical utilization of such parts. Rolling contact fatigue of some steels obtained out of prealloyed powders Astaloy CrM, Atomet 4601, Atomet 4901 and powder blends iron-carbon-nickel by hot forging is studied in the present paper. Effect of various kinds of heat and thermomechanical treatment on rolling contact fatigue is determined. Thermomechanical treatment provides optimal values of rolling contact fatigue. In this case steel structure contains up to 40% of retained metastable austenite which is transformed to martensite on trials. Thus typically crack is generated on residual pores and non-metallic inclusions instead of martensite zones in wrought steels.