An attempt was made to synthesize Cu/B4C surface composite using friction stir processing（FSP） and to analyze the influence of tool rotational speed on microstructure and sliding wear behavior of the composite. The ...An attempt was made to synthesize Cu/B4C surface composite using friction stir processing（FSP） and to analyze the influence of tool rotational speed on microstructure and sliding wear behavior of the composite. The tool rotational speed was varied from 800 to 1200 r/min in step of 200 r/min. The traverse speed, axial force, groove width and tool pin profile were kept constant. Optical microscopy and scanning electron microscopy were used to study the microstructure of the fabricated surface composites. The sliding wear behavior was evaluated using a pin-on-disc apparatus. The results indicate that the tool rotational speed significantly influences the area of the surface composite and the distribution of B4C particles. Higher rotational speed exhibits homogenous distribution of B4C particles, while lower rotational speed causes poor distribution of B4C particles in the surface composite. The effects of tool rotational speed on the grain size, microhardness, wear rate, worn surface and wear debris were reported.展开更多
The aim of present work is fabrication of Al/Al2Cu in situ nanocomposite by friction stir processing(FSP)as well asinvestigation of FPS parameters such as rotational speed,travel speed,number of FSP passes,and pin pro...The aim of present work is fabrication of Al/Al2Cu in situ nanocomposite by friction stir processing(FSP)as well asinvestigation of FPS parameters such as rotational speed,travel speed,number of FSP passes,and pin profile on the microstructure,chemical reaction,and microhardness of Al based nanocomposite.The Al2Cu particles were formed rapidly due to mechanicallyactivated effect of FSP as well as high heat generation due to Al?Cu exothermic reaction.The microstructure of the nanocompositesconsisted of a finer grained aluminium matrix(~15μm),unreacted Cu nanoparticles(~40nm),and reinforcement nanoparticles ofAl2Cu.Irregular morphology of Al2Cu is attributed to the local melting during FSP.Pin diameter has a higher effect on themicrostructure and hardness values.The hardness measurements exhibited enhancement by57%compared with the base metal.展开更多
A356alloy was used as the base metal to produce boron carbide(B4C)/A356composites using friction stir processing(FSP).The microstructural and mechanical properties of B4C/A356composites were optimized using artificial...A356alloy was used as the base metal to produce boron carbide(B4C)/A356composites using friction stir processing(FSP).The microstructural and mechanical properties of B4C/A356composites were optimized using artificial neural network(ANN)and non-dominated sorting genetic algorithm-II(NSGA-II).Firstly,microstructural properties of the composites fabricated in different processing conditions were investigated.Results show that FSP parameters such as rotational speed,traverse speed and tool pin profile significantly affect the size of the primary silicon(Si)particles of the base metal,as well as the dispersion quality and volume fraction of reinforcing B4C particles in the composite layer.Higher rotational to traverse speeds ratio accompanied by threaded pin profile leads to better particles distribution,finer Si particles and smaller B4C agglomerations.Secondly,hardness and tensile tests were performed to study mechanical properties of the composites.FSP changes the fracture mechanism from brittle form in the as-received metal to very ductile form in the FSPed specimens.Then,a relation between the FSP parameters and microstructural and mechanical properties of the composites was established using ANN.A modified NSGA-II by incorporating diversity preserving mechanism called theεelimination algorithm was employed to obtain the Pareto-optimal set of FSP parameters.展开更多
文摘An attempt was made to synthesize Cu/B4C surface composite using friction stir processing（FSP） and to analyze the influence of tool rotational speed on microstructure and sliding wear behavior of the composite. The tool rotational speed was varied from 800 to 1200 r/min in step of 200 r/min. The traverse speed, axial force, groove width and tool pin profile were kept constant. Optical microscopy and scanning electron microscopy were used to study the microstructure of the fabricated surface composites. The sliding wear behavior was evaluated using a pin-on-disc apparatus. The results indicate that the tool rotational speed significantly influences the area of the surface composite and the distribution of B4C particles. Higher rotational speed exhibits homogenous distribution of B4C particles, while lower rotational speed causes poor distribution of B4C particles in the surface composite. The effects of tool rotational speed on the grain size, microhardness, wear rate, worn surface and wear debris were reported.
基金Islamic Azad University,the Ahwaz Branches for financial support of this research work
文摘The aim of present work is fabrication of Al/Al2Cu in situ nanocomposite by friction stir processing(FSP)as well asinvestigation of FPS parameters such as rotational speed,travel speed,number of FSP passes,and pin profile on the microstructure,chemical reaction,and microhardness of Al based nanocomposite.The Al2Cu particles were formed rapidly due to mechanicallyactivated effect of FSP as well as high heat generation due to Al?Cu exothermic reaction.The microstructure of the nanocompositesconsisted of a finer grained aluminium matrix(~15μm),unreacted Cu nanoparticles(~40nm),and reinforcement nanoparticles ofAl2Cu.Irregular morphology of Al2Cu is attributed to the local melting during FSP.Pin diameter has a higher effect on themicrostructure and hardness values.The hardness measurements exhibited enhancement by57%compared with the base metal.
文摘A356alloy was used as the base metal to produce boron carbide(B4C)/A356composites using friction stir processing(FSP).The microstructural and mechanical properties of B4C/A356composites were optimized using artificial neural network(ANN)and non-dominated sorting genetic algorithm-II(NSGA-II).Firstly,microstructural properties of the composites fabricated in different processing conditions were investigated.Results show that FSP parameters such as rotational speed,traverse speed and tool pin profile significantly affect the size of the primary silicon(Si)particles of the base metal,as well as the dispersion quality and volume fraction of reinforcing B4C particles in the composite layer.Higher rotational to traverse speeds ratio accompanied by threaded pin profile leads to better particles distribution,finer Si particles and smaller B4C agglomerations.Secondly,hardness and tensile tests were performed to study mechanical properties of the composites.FSP changes the fracture mechanism from brittle form in the as-received metal to very ductile form in the FSPed specimens.Then,a relation between the FSP parameters and microstructural and mechanical properties of the composites was established using ANN.A modified NSGA-II by incorporating diversity preserving mechanism called theεelimination algorithm was employed to obtain the Pareto-optimal set of FSP parameters.
