International audienceThis paper deals with the development of a novel and predictive finite element method (FEM) model coupling electrical, thermal, and mechanical time-dependent contributions for simulating the behavior of a powdery material submitted to a spark plasma sintering (SPS) treatment by using COMSOL Multiphysics (R) software. The original approach of this work lies in the use of the modified Cam-Clay model to solve the mechanical phenomenon occurring during a SPS sintering treatment. As the powder properties and behaviors are different from the final sintered material and display a nonlinear dependence as a function of temperature and pressure, the model includes the description of the sample densification. In this way, numerical and experimental results obtained on conductive model material (aluminum) such as temperature, stress distributions, and shrinkage, were directly compared. This FEM model demonstrated the ability to predict the powder behavior during temperature-controlled experiments precisely, as they are typically performed in the SPS technique. This approach exhibits a remarkable level of interest because it takes into account the nature of the material and also the specific characteristics of the powder studied
This paper presents the results of a study on the impact of a precipitation hardening treatment on the mechanical properties of 17-4PH stainless steel open-cell foams produced using a powder-metallurgy-based process patented by the National Research Council Canada (NRC). Pre-alloyed powder was used to manufacture stainless steel (SS) foams with either medium or high porosity by changing the nature of the organic binder used to process the porous materials. Some of these were kept in the as-sintered state, while others were submitted to the H900 precipitation hardening treatment frequently prescribed for 17-4PH stainless steels.Metallurgical and physical characterization was carried out on the resulting materials, along with mechanical testing at the micro (indentation testing) and macro (compressive testing) scales. It was found that the Medium-Porosity Foams (MPF) and High-Porosity Foams (HPF) had very different morphologies, the HPFs having a delicate porous structure featuring thin sintered walls with many openings (a.k.a. windows) between the main cells, while the MPFs exhibited much thicker walls with few windows connecting the larger pores. As expected from these foam morphologies, the mechanical properties of MPFs were much higher than those of the more porous and delicate HPF materials. For both foam types, the average mechanical properties were improved by the H900 treatment. A comparison with compressive properties of 17-4PH foams taken from the literature resulted in reasonable agreement. However, the large scatter observed on the average compressive properties of the NRC foams and the slightly different structure/composition of the literature materials mean that any comparison between these porous alloys must be interpreted with caution.
We report for the first time laser action in resonantly-pumped transparent polycrystalline Er:YAG ceramic developed through a 2-step approach combining spark plasma sintering and HIP post treatment. Microstructural and spectroscopic properties, as well as the laser performance of large scale 0.5at.% Er:YAG transparent polycrystalline ceramic are discussed. A maximum slope efficiency of ∼31% and optical-optical efficiency of 20% was measured.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.