Preparation and microstructural characterization of five-layered aluminium-aluminium oxide functionally graded material

In this research, the metallic phase Aluminium (Al) and the ceramic phase Aluminium Oxide (Al2O3) were combined in different proportions for the preparation of five-layered Al-Al2O3 functionally graded material. Delamination or crack is the common problem at the metal-ceramic interface because of the large difference in material properties. Therefore, the main objective of this research was to investigate the defects within the layer during processing of the graded structure. The compositions of different weight percentages of five-layered structure are 100%Al+0%Al2O3, 95%Al+5%Al2O3, 90%Al+10%Al2O3, 85%Al+15%Al2O3 and 80%Al+20%Al2O3. During preparation of the graded composite structure, conventional two-step sintering cycle was followed. Heating rate 2°C/min, sintering temperature 630°C and sintering time 3 hours were maintained. It was observed that there was uniform distribution of Al2O3 ceramic particle in the Al matrix with the minimum of agglomeration, all interfaces were almost parallel with layers boundary and gradual transition occurred from first layer to fifth layer which confirmed the proper preparation processes of the five-layered graded composite structure. In addition, it was evident that there was no existence of crack within any layer or interface of the prepared composite structure

Investigation on microstructure and hardness of aluminium-Aluminium oxide functionally graded material

This study investigated the microstructure and hardness of aluminium-aluminium oxide (Al-Al2O3) functionally graded material (FGM). Preparation of metal-ceramic functionally graded material was carried out following powder metallurgy (PM) route. Four-layered aluminium-aluminium oxide (Al-Al2O3) graded composite structure was processed using 0%, 5%, 10% and 15% (from first layer to fourth layer) aluminium oxide as ceramic concentration. A cylindrical steel die was used for the fabrication process of the FGM green compact. The green compact was prepared by applying cold pressing technique using a hydraulic press. The sintering process was implemented at 600 °C sintering temperature and 3 h sintering time using 2-step cycle. Microstructural characterization of the sample was conducted layer by layer using high resolution optical microscopy (OM). Hardness of the sample was also performed layer by layer using Vickers microhardness tester. The obtained results revealed that there is a uniform ceramic particle distribution within the metallic phase. From the microstructural observation it was clear that smooth transition occurred from one layer to next layer and each interface was distinct. It was also observed that there is a steady increase in layer hardness with the increase in ceramic concentration