10 research outputs found
Effect of mechanical alloying and annealing on the sintering behaviour of AstaloyCrL powders with SiC and carbon addition
An Investigation of Evolutions during Liquid Phase Sintering of Systems with Volatile Components
In this paper, the possibility of elephant foot phenomenon in sintered alloys with volatile components has been studied. To do this, Cu-28Zn brass samples were sintered at the range of 890-970°C for 20 min. The in situ images from brass samples were taken at various sintering conditions. It is concluded that although liquid is pulled down by gravity, but elephant phenomenon was not appeared in these compacts. Instead, the samples were swelled. Chemical composition change and pores coarsening due to zinc evaporation could be considered as the main cause of swelling in brass compacts
Densification and volumetric change during supersolidus liquid phase sintering of prealloyed brass Cu28Zn powder: Modeling and optimization
An investigation has been made to use response surface methodology and
central composite rotatable design for modeling and optimizing the effect of
sintering variables on densification of prealloyed Cu28Zn brass powder
during supersolidus liquid phase sintering. The mathematical equations were
derived to predict sintered density, densification parameter, porosity
percentage and volumetric change of samples using second order regression
analysis. As well as the adequacy of models was evaluated by analysis of
variance technique at 95% confidence level. Finally, the influence and
interaction of sintering variables, on achieving any desired properties was
demonstrated graphically in contour and three dimensional plots. In order to
better analyze the samples, microstructure evaluation was carried out. It
was concluded that response surface methodology based on central composite
rotatable design, is an economical way to obtain arbitrary information with
performing the fewest number of experiments in a short period of time
DENSIFICATION AND MICROSTRUCTURE CHARACTERISTICS OF A PREALLOYED ALPHA BRASS POWDER PROCESSED BY LIQUID PHASE SINTERING
The rapidly solidified prealloyed alpha brass powder with a size range of 40 to 100 μm produced by water
atomization process was consolidated using liquid phase sintering process. The relationships between sintering
temperature, physic-mechanical properties and microstructural characteristics were investigated. Maximum
densification was obtained at 930 °C, under 600 MPa compacting pressure, with 60 min holding time. The
microstructure of the sintered brass was influenced by dezincification and structural coarsening during supersolidus
liquid phase sintering. As a consequence of Kirkendall effect atomic motion between Cu and Zn atoms caused to
dezincification at the grain boundaries and formation of ZnO particles on the pore surfaces. It was concluded that
microstructural analysis is in a well agreement with obtained physical and mechanical properties. Also, the amount of
liquid phase, which depends on sintering temperature, results in different load bearing cross section areas, and it
affects the type of fracture morphologies