Nanostructured FeNi and FeNiGr alloys were successfully synthesized by the mechanical alloying technique. The alloys formation and different magnetic properties were studied as a function of milling time in the range of 0 to 30h by X-ray diffraction (XRD) technique, Scanning Electron Microscope (SEM) analysis and a Vibrating Sample Magnetometer (VSM) process. The X-ray diffraction study confirmed the apparition of the α-FeNi alloy after 5h of milling with an average crystallite size of 26.80nm. The crystallite size obtained after 30h of milling is 10.13nm, While, the lattice deformation increases from 0.431 to 0.935%. in addition, the analysis of the magnetization curves of the Fe-Ni alloys revealed original magnetic properties: super paramagnetic behavior, and especially saturation magnetization and significant coercivity. ​​​​​​​ Furthermore, the addition of graphene into FeNi alloy, reduced its crystallite size from 11.56 to 6.65 nm, and increases the lattice strain and lattice parameter from 0.631 to 0.748% and from 0.28686 to 0.28704nm, respectively. Which, enhanced these magnetic properties, by increasing its coercivity (Hc) from 16. 07 to 135.42 Oe and Mr from 1.73 to 5.87 emu/g, while the magnetization saturation is decreased from 153.25 to 123.06 emu/g.

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The present article tends to predict the effective thermal properties of porous biocomposites materials. The composites matrix consists on porous materials namely gypsum and the reinforcement is a natural fiber as date palm fibers. The numerical study is done using Comsol software resolving the heat transfer equation. The results are fitted with theoretical model and experimental results. The results of this study indicate that the porosity has an effect on the Effective thermal conductivity biocompoites.