The present research work aims to study the heat treatment effect on the structural and mechanical properties of the tool steel AISI D2. The steel has undergone a double treatment. First, the iron-based alloy was subjected to a normalizing, the explored temperatures are 975, 1025 and 1075°C for a holding time of 1 hour. Then, the steel is annealed at temperatures ranging from 250 to 650°C for 2 hours. The structural and mechanical properties of the tool steel AISI D2 was studied by several experimental methods: hardness measurement, optical microscopy, scanning electron microscopy and X-ray diffraction. After the heat treatments, the mechanical properties of the steel decreased compared to as-received state. According to the microscopic study, the softening is due to the precipitation of cementite present as spherical and isolated particles in a matrix of ferrite.

The study of the influence of heat treatment on changes of mechanical and structural properties of Steel Ni-based Alloy is a highly interdisciplinary topic at the interface of the physical chemistry of metallic materials, which also helps in environmental and economic protection.After heat treatment, the structural and micro-structural studies for the different transformation temperature led to identify phases formed and the morphology. This work has been carried out using different techniques: X-ray diffraction, optical microscopy and scanning electron microscopy.

Hastelloy C2000 is a superalloy used in the chemical processing, pollution control and waste treatment industries. This alloy contains a nominal amount of 52-60% of Ni, 15-31% of Cr, 9-16% of Mo, and small additions of other elements such as iron, copper, tungsten, etc. Its matrix is austenitic and its structure is face-centered cubic. The objective of our work is to study the structure of the Hastelloy C2000 and this by a heat treatment at four temperatures: 700 degrees C, 800 degrees C, 900 degrees C and 1000 C-omicron with a prolonged maintenance at each temperature during three hours. The monitoring of the structure is performed by using the X-ray diffraction (XRD). The X-ray diffraction spectra obtained after the heat treatments, show the presence of peaks of the precipitates and the peaks of the austenite phase. For the crystallographic parameters of the mesh before and after the four heats treatments, we remark an increase of the parameter a and the volume of the mesh as a function of treatment temperature.

This study is aimed at investigating the drying kinetic of Myrtus communis L. leaves by fluidisation at controlled temperatures and air speeds and fitting it to eight mathematical models existing in the literature. Five experiences were carried out for three airflows (Va=1, 0.8 and 0.3 m/s) and three temperatures (40, 50, 60 degrees C). Fitting of experimental drying curves to the models pointed out that "Modified Henderson and Pabis" model is the most suitable for describing the drying kinetic of this product.

Although aluminum is sometimes used alone, we often add to it small amounts of other metals in order to obtain alloys with specific qualities. Some elements of the alloy increase the mechanical resistance or the resistance to corrosion. Other improve: the aptitude to manufacturing; malleability; weldability and; the resistance to high temperatures. Since the range of diverse alloys is very extended, so allows to find that which is most suitable to the envisaged use constraints. Therefore the mechanical properties of aluminum can be modified by the addition of other metals, notably magnesium which considerably contribute to the improvement of mechanical typical features of various alloys and significantly improves the aptitudes to the manufacturing of realised parts. The current study consists of modeling the mechanical properties of the AlCuMg alloys as well as studying the addition effect of magnesium upon the cooling process and upon the evolution of the properties in question.

Hastelloy C2000 is a nickel-base superalloy. With the addition of copper to nickel-chromium-molybdenum system, it is resistant to a wide range of corrosive chemicals as well as the combination of molybdenum and copper creates an excellent corrosion resistance to reducing media, while the high content of the chrome provides a good oxidation resistance. Its structure is face-centered cubic. The value of our work is to study the stability of the Hastelloy C2000 on its microstructure and mechanical properties and this by a heat treatment at four temperatures: 700 degrees C, 800 degrees C, 900 degrees C and 1000 degrees C with a prolonged maintenance at each temperature for three hours. The monitoring of these two aspects is performed using the following experimentals techniques: optical microscopy and hardness measurement. After heat treatment, the pictures obtained by optical microscopy revealed the presence of different morphologies of carbides, joints and inside the grains, also we remark the appearance of the discontinuous transformations and the coalescence phenomenon of grain to form a larger area of precipitation. For hardness in the over-aging, it attains a final value of 47 for the four samples treated at 700 degrees C, 800 degrees C, 900 degrees C and 1000 degrees C.

This study is aimed at determining the drying speed of Myrtus communis L. by fluidization according to parameters of influence. It is based on exploiting the results of previous experimental studies, as well as the similarity between drying kinetic and chemical kinetic in order to establish a universal model. The considered parameters are: drying air temperature Tp, product absolute humidity Ns and drying air speed va.

This study is focused on the structural hardening of ternary Pb-Cd-Mg alloys. The reequilibration of Pb-Cd-Mg alloys was studied by different experimental methods: hardness measurements, optical microscopy and X-ray diffraction. Alloys concerned are : Pb2%Cd1%Mg, Pb2%Cd2%Mg et Pb2%Cd3%Mg. Two structural states were considered: as-cast alloy and rehomogenized alloy. The explored temperatures were 20 degrees C and 80 degrees C. The structure evolution of Pb-Cd-Mg alloys to the equilibrium state occurs in two stages: the first is characterized by a discontinuous transformation hardening; the second occurs after aging, it is characterized by softening coarse discontinuous precipitation. The addition of magnesium slightly increases the hardness and slow kinetics of the hardening transformation.

The superalloy Hastelloy G30 (trademark of Haynes International, Inc.) is an alloy with a high proportion of nickel, characterized by a high corrosion resistance in environments containing extra oxidizing acids. The alloy consists essentially of 43% of nickel with a proportion of chromium which varies from 28 to 31.5% and from 13 to 17% for iron. Its matrix is austenitic and its structure is face-centered cubic. The objective of this work is to treat the alloy G30 thermally at 4 different temperatures 700 degrees C, 800 degrees C, 900 degrees C and 1000 degrees C for 3 hours. Indeed, we followed the progression of structural and mechanical properties. The micro structural evolution influence slightly on the mechanical properties of the alloy G30: hardness of the alloys treated at 700 degrees C and 800 degrees C is equal to 46 HRF and that of the alloys treated at 900 degrees C and 1000 degrees C is 46.25 HRF. The images obtained by optical microscopy revealed the presence of carbides at the joints and inside the grains. The X-ray diffraction spectra obtained after the isothermal treatments showed the presence of peaks of the precipitates and the peaks of the austenite phase.

The phenomenon of aging and overaging of Pb-Cd-Bi-Sn alloys is characterized by a discontinuous processing and a continuous reaction, it's hardening and softening. The presence of tin slows kinetics of hardening transformation and increases the hardness. Our study is devoted to determine precipitation type, nature and phase morphology of precipitates and the intensity of hardening in the quaternary alloys Pb-Cd-Bi-Sn. The return to equilibrium of supersaturated alloys Pb-Cd-Sn-Bi has been studied by different techniques: hardness, optical microscopy and X-ray diffraction. Two structural states were considered: raw casting alloy and rehomogenized alloy. The studied alloys are: Pb2% Cd1% Bi, Pb 2% Cd2% Bi, Pb 2% Cd3% Bi with different percentages of tin 0.25% Sn, 0.5% Sn, 1.25% Sn and 2% Sn. Experimental temperatures are 20 degrees C and 80 degrees C. Bismuth accelerates the hardening reaction, while tin has a retarding effect on the hardening process.

The development of industries in Morocco has led to the multiplication and diversification of air pollutants.The dispersion of the pollutants discharged by the weather favors. In this context, this work is devoted to modeling and simulation of the effects of these weather conditions, which are the temperature, the speed and  the wind direction ,on the dispersion of pollutants from chimney sulfuric workshop of OCP Jorf-Lasfar ie SO2, SO3. Advanced numerical simulation tool was used with a method of analysis  to study the effects of weather conditions on the atmospheric dispersion, followed by a critical study results that permits to deduce that the most disperse pollutants is  SO2.

The solid-liquid equilibria of the quasi quaternary system H 2 O Zn(NO 3 ) 2 ,6H 2 O Cu(NO 3 ) 2 ,3H 2 O-NH 4 NO 3 were studied at 25°C by using a synthetic method based on conductivity measurements. Three isoplethic sections has been established at 25°C and the stable solid phases which appear are: NH 4 NO 3 (IV), Zn(NO 3 ) 2 ,6H 2 O, Cu(NO 3 ) 2 ,3H 2 O and metastable Cu(NO 3 ),2.5H 2 O. Neither double salts, nor mixed crystals are observed at these temperature and composition range.

The solid-liquid equilibria of the quasi quaternary system H2O Zn(NO3)2,6H2O Cu(NO3)2,3H2O-NH4NO3 were studied at 25°C by using a synthetic method based on conductivity measurements.Three isoplethic sections has been established at 25°C and the stable solid phases which appear are:NH4NO3 (IV), Zn(NO3)2,6H2O, Cu(NO3)2,3H2O and metastable Cu(NO3),2.5H2O.Neither double salts, nor mixed crystals are observed at these temperature and composition range.

Structural hardening of PbSbAl alloys is characterized by two stages: the first is characterized by a hardening continuous reaction and a softening discontinuous transformation. The second is characterized by a softening discontinuous precipitation. The influence of minor additions of aluminum results in increasing of hardness. Two structural states were considered: as-cast and rehomogenized alloys. The contents of Aluminium (Al) are 0.16%, 0.8% and 1.4% (in weight percent). Those of antimony (Sb) are 1.5% and 2%. The explored temperatures are essentially 20 degrees C and 80 degrees C. This last is chosen because it corresponds to the temperature of ripening of battery plates as well as the extreme temperature of its operation.

Molded Steel with manganese have approximately 1,2% C and 12% Mn, this high proportion of manganese gives to this alloy a stable austenitic structure on a room temperature. The experimental methods used for metallurgical studies are spark optical emission spectroscopy, optical microscopy, scanning electron microscopy, micro-hardness and hardnesss test. Steel 1 is heat-treated constitued by 15,516 % of manganese, 2,677 % of chromuim and 1,286 % of carbon. Steel 2 is mechanically treated contains 13,454 % of manganese, 1,721 % of chromuim and 1,213 % of carbon . Steel 1 has sustained quench at 1070°C, for two differents maintaining times on oven 30 and 50 minutes for a thickness of 150 millimeters then for two differents thickness 100 and 150 millimeters for a time of 50 minutes. When maintaining time on the oven increase for low dimension, surface’s alloy become more ductile. We have applied a mechanical treatement manually on steel 2 surface, his hardness increase significantly.

The phenomenon of aging and overaging of PbCdBiMg alloys is characterized by continuous and discontinuous transformation, it is hardening and softening characterized by a precipitation of cadmium. In general, the magnesium addition increases the hardness and delays the kinetics of the hardening processing. Indeed, the study of the return to equilibrium of supersaturated hardened alloys PbCdBiMg was carried out by various experimental techniques: hardness, micro hardness, optical microscopy and X-ray diffraction. Two structural states were considered: raw casting alloys and rehomogenized alloys. The alloys concerned are: Pb2% Cd1% Bi and Pb 2% Cd3% Bi with various magnesium proportions: 0.12% Mg, 1% Mg, 2% Mg and 3% Mg. The experimental temperatures are 20 degrees C and 80 degrees C. Bismuth accelerates the curing reaction and magnesium slightly retards the transformation.

In order to master and improve the quality and properties of the final products, the major industrial challenge lies in the possibility of controlling the morphology, size of microstructures that reside within the molded pieces, as well as their defects; this is the fundamental reason according to which we are more and more interested in mastering the growth and germination of such alloys, as well as the developing structures, at the time of solidification process. The modeling reveals as a valuable aid in the mastery of the formation of such heterogeneousness: segregation cells that are incompatible with industrial requirements.  The whole work focuses upon the modeling of the segregation phenomenon of the four hypoeutectic alloys, Al1%Cu, Al2%Cu, Al3%Cu et Al4%Cu, as well as the copper effect upon certain mechanical properties of aluminum. Usually, the microstructure and mechanical behavior of such alloys as Al-Cu are directly influenced by some parameters such as composition, cooling velocity and homogenization process.

In order to master and improve the quality and properties of the final products, the major industrial challenge lies in the possibility of controlling the morphology, size of microstructures that reside within the molded pieces, as well as their defects; this is the fundamental reason according to which we are more and more interested in mastering the growth and germination of such alloys, as well as the developing structures, at the time of solidification process. The modeling reveals as a valuable aid in the mastery of the formation of such heterogeneousness: segregation cells that are incompatible with industrial requirements. The whole work focuses upon the modeling of the segregation phenomenon of the four hypoeutectic alloys, Al1%Sn, Al2%Sn, Al3%Sn and Al4%Sn, as well as the tin effect upon certain mechanical properties of aluminum. Usually, the microstructure and mechanical  behavior of such alloys as Al-Sn are directly influenced by some parameters such as composition, cooling velocity and homogenization process.