Mechanically Activated Self-Propagating High Temperature Synthesis (MASHS) Applied to the MoSi<sub>2</sub> and FeSi<sub>2</sub> Phase Formation

In-situ time-resolved X-ray diffraction experiments applied to self-sustained reactions from mechanically activated mixtures

Resume . Le procede MASHS (Mechanically activated self-propagating high-temperature synthesis) apparait etre un procede alternatif interessant pour elaborer des materiaux tels que des ceramiques, des composites ou des intermetalliques. La formation au cours d'une reaction de combustion autoentretenue d'intermetalliques, tels que NbAlj et M0S12, a ete suivie in-situ et en temps reel en couplant la diffraction des rayons X, produits par le rayonnement synchrotron (Ligne D43, LURE - Orsay) et, une thermographie infrarouge. A partir de temps d'acquisition tres courts (de 30 ms a 100ms par diffractogrammes), il a ete possible de determiner simultanement les evolutions structurales et thermiques.…

Enhancement of self-sustaining reaction by mechanical activation: case of an FeSi system

Mechanical high energy ball milling of an Fe2Si elemental powders mixture was used to activate a self sustaining combustion reaction or so-called self-propagating high-temperature synthesis (SHS) to form iron disilicide, a reaction for which the thermodynamic criterion is not favorable. A complete characterization of the milled powders before reaction was performed with energy dispersive X-ray spectrometry, specific surface measurements and X-ray diffraction profile analysis. Thermal and structural information describing the combustion front initiated by heating up a sample to 400°C in a Fe‐Si system is communicated. In order to isolate the phases involved in the gasless reaction, a time-re…

Simultaneous synthesis and consolidation of nanostructured MoSi2

The mechanically activated combustion reaction in the Fe–Si system: in situ time-resolved synchrotron investigations

Mechanical high-energy ball milling of Fe+2Si elemental powder mixtures was used to activate self sustaining combustion reaction in the case of iron disilicide synthesis. The reaction path as well as the influence of the microstructural parameters on phase transformation have been investigated in detail. Time-resolved X-ray diffraction (TRXRD) using the fast recording kinetics offered by the synchrotron radiation was coupled to an infrared camera in order to study the internal structure of the combustion wave. The crystallite size and the amount of mechanically induced phases play an important role during the combustion; the reaction path and the end product composition mainly depend on the…

The mechanically activated combustion reaction in the Fe-Si system : in situ time-resolved synchrotron investigation

"In situ synchrotron charcterization of mechanically activated self - propagating high temperature synthesis applied in Mo - Si system

Nanocrystalline FeAl Synthesis by MASHS with <i>In Situ</i> and Post Mortem Characterizations

Assisted self-sustaining combustion reaction in the Fe–Si system: Mechanical and chemical activation

Abstract This work presents original investigations carried out to improve the activated self-propagating high-temperature synthesis (SHS) process in the Fe–Si system: different ignition modes are tested (volume heating as opposed to a local ignition source), and the use of additive is considered in order to enhance the SHS type reactivity in the Fe–Si system. When 20 wt.% of KNO 3 is added to the reactive mixture, the fast (>20 mm s −1 ), stable and self-sustaining combustion reaction produces a very fine FeSi + α-FeSi 2 structure. Infrared thermography (IR) as well as post-mortem analysis (SEM, EDXS, XRD) was used to understand the mechanism behind the chemical activation process when KNO…

'Enhancement of self - sustaining reaction by mechanical activation : case of Fe - Si systeme"

Mechanical activation effect on the self-sustaining combustion reaction in the Mo–Si system

Abstract Nanostructured molybdenum disilicide (MoSi2) was synthesized using an alternative route called MASHS (mechanically activated self-propagating high-temperature synthesis). This original process combines a short duration ball milling (MA) with a self-sustaining combustion (SHS). These two steps were investigated. The microstructure evolution of the powder mixture during mechanical activation was monitored using XRD profile analysis and TEM investigations. Short duration ball milling of (Mo+2Si) powder produces Mo and Si nanocrystallites into micrometric particles. It was demonstrated that pure α-MoSi2 with nanometric structure (DMoSi2=88 nm) could be produced via a very fast combusti…