non-conventional methods; they are relatively low costs and characteristic isotropic properties. Therefore, AMCs have been applied successfully to structural components, especially in the automotive and aviation industries, and the number of applications is expected to increase with the development of low-cost processing methods [10, 11]. To improve the structure and properties of particulate reinforced MMCs various processing techniques have evolved over the last 20 years. The potential for forming processes based upon semi-solid metal alloys was first recognized in the early 1970s. The microstructure of a suitable alloy comprises spheroidal particles of solid surrounded by liquid phase of a lower melting point, rather than the interlocking tree-like dendrites of conventionally cast alloy. It is this microstructure that gives the material its thixotropic properties, i.e. when sheared the material flows, but when allowed to stand, it thickens. Thixoforming is one member of semi-solid forming processes and it possesses characteristics of both casting and forging [4, 7, 8]. For this reason, it was interesting to develop a new composite from scrap aluminium chips reinforced with TiN +Al2O3 ceramic powders and to examine its tailored beahviour of these composites. In the present work, laser cutting process of aluminium matrix composites obtained from scrap chips reinforced with hard ceramics (TiN + Al2O3) were carried out. The thermal effects of laser cutting and effects of main operating parameters such as laser power, and cutting speed on the cutting edge and on the cutting surface were examined. The evolution of the microhardness underneath the cutting surface due to laser power is also examined. The composite used in this study was produced through combined method of powder metallurgical (P/M) and thixoforming (Semi solid). Microstructure of cutting edge and cutting surfaces are investigated in detail by scanning electron microscopy (SEM). Cutting surfaces have been analyzed with 3D optical surface roughness-meter (3D–SurfaScan). Roughness evaluations were taken as optimization criteria as a function of the cutting surface and cutting parameters (power, speed, gas pressure etc.) that have been carried out by Taguchi method. A simple and useful tool was proposed for using in real manufacturing environment. 12.2 Experimental Conditions 12.2.1 Manufacturing of Composites and Microstructural Evaluation Composition of the specimens designed in this work was arranged as follows (Table 12.1): basic reinforcement used here are Al203 and TiN is variable between 10% and 30%. As secondary reinforcements, Ti, Cu and Ni were used. A little amount h-BN was added to the microstructure because Boron Nitride (BN) is a very suitable ceramic powder because of their high intrinsic thermal conductivity. It is not sensitive at all against moisture and it is very suitable for lubrication effect during mixing and compacting of composition. All of three types of composites will be called here after TiN-I, TiN-II and TiN-III depending on the amount of TiN respectively. Processing route has been carried out through combined process of powder metallurgical (P/M) and thixoforming. Firstly, all of the element of this composition have been mixed and milled in a pulverize device during 4 h by using a protection and successfully ball milled (4000 rpm) during 1 h and compacted by CIP (Cold Isostatic Pressure) at a pressure of 250 MPa and after that thixo forming sintering after heating at the temperature of 700 C for 45 min under argon inert atmosphere, then it was cooled in the oven. After manufacturing of the composites, microstructural evaluation has been carried out for each composite. The dispersion of reinforcement particles in the matrix and interface at matrix/reinforcements was evaluated. Microhardness tests have been carried out on the polished and etched specimens. Certain basic mechanical parameters have been given here as an indicative results of these composites. Table 12.1 Chemical compositions of three different composites designed in this work Specimen name AlMatrix Al2O3 (wt%) TiN (wt%) Ti (wt%) Cu (wt%) Ni (wt%) BN TiN-I B 10 10 5 5 5 1 TiN-II B 10 20 5 5 5 1 TiN-III B 10 30 5 5 5 1 116 S. Ezeddini et al.
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