The Effect of Relative Porosity on the Survivability of a Powder Metallurgy Part During Ejection

The desire to produce functional powder metallurgy (PM) components has resulted in higher compression forces during compaction. This in turn increases the ejection stresses and therefore the possibility of failure during ejection. This failure can be caused by sprig back during ejection due to frictional forces that are generated between the powder part and the die walls. In order to predict these factors a stress analysis of the powder part during ejection was done. Due to complexity, finite element analysis was used to model the powder during compaction and ejection. Since the ejection stage is the most critical stage of the PM process, it is essential to understand the factors that determine the survivability of a part during this stage. This work uses experimental data, finite element modeling and reliability analysis to determine the probability of failure of metallic powder components during the ejection phase. The results show that there is an increased possibility of failure during ejection as compaction pressure is increased. This information can be used by designers and process planners to determine the optimal process parameters that need to be adopted for optimal outcomes during powder metallurgy.

The Effect of Relative Porosity on the Survivability of a Powder Metallurgy Part During Ejection

The desire to produce functional powder metallurgy (PM) components has resulted in higher compression forces during compaction. This in turn increases the ejection stresses and therefore the possibility of failure during ejection. This failure can be caused by sprig back during ejection due to frictional forces that are generated between the powder part and the die walls. In order to predict these factors a stress analysis of the powder part during ejection was done. Due to complexity, finite element analysis was used to model the powder during compaction and ejection. Since the ejection stage is the most critical stage of the PM process, it is essential to understand the factors that determine the survivability of a part during this stage. This work uses experimental data, finite element modeling and reliability analysis to determine the probability of failure of metallic powder components during the ejection phase. The results show that there is an increased possibility of failure during ejection as compaction pressure is increased. This information can be used by designers and process planners to determine the optimal process parameters that need to be adopted for optimal outcomes during powder metallurgy.

Nanostructured strain hardened aluminum-magnesium alloys modified by C60 fullerene obtained by powder metallurgy. Part 1. Effect of magnesium concentration on the structure and phase composition of powders

This paper provides the first part of the study on the magnesium effect on the structural phase composition, physical and mechanical properties of nanostructured aluminum-magnesium composite materials with the composition AlxMgy + 0.3 wt.% C60 fullerene. Composite powders were obtained by the simultaneous mechanical activation of initial materials in a planetary ball mill in an argon atmosphere. It was found that the obtained powders have a complex hierarchical structure made up of 50–200 μm aggregates consisting of 5–10 μm strong high-density agglomerates, which in turn are a combination of nanoscale (30–60 nm) crystallites. It was found that the increase in magnesium concentration in the composite up to 18 wt.% makes it possible to obtain crystallites with an average size of less than 30 nm during mechanical activation, while the size of aggregates is less than 50 μm. The maximum solubility of magnesium in aluminum with a crystallite size of 30–70 nm during mechanical activation was 15 wt.% (17 at.%). Using the differential scanning calorimetry method, it was found that nanostructured composites undergo irreversible structural phase transformations during heat treatment in a temperature range of 250–400 °C: recrystallization, decomposition of the α-solid solution of magnesium in aluminum and formation of intermetallic β-(Al3Mg2), γ-(Al12Mg17) and carbide (Al4C3) phases. In addition, the Raman spectra contain peaks that, according to some sources, correspond to covalent compounds of aluminum with C60 fullerene – aluminum-fullerene complexes. The data obtained will be used in further research to determine parameters for the thermobaric treatment of nanocmposite powder mixtures in order to obtain and test bulk samples.