Microstructure evolutions and mechanical properties of nano-SiC-fortified AA7075 friction stir weldment: The role of second pass processing

Process Parameters Optimization for Producing AA6061/TiB2 Composites by Friction Stir Processing

“…The similar observations were found in earlier work of M.M. El Rayes, A. Hamdollahzadeha et al and M. Barmouz et al [47,48,49]. The TiB2 particles restrains the movement of grains which in turn reduces the grain growth and causes dynamic crystallization.…”

Microstructural, mechanical and wear characteristics of aluminum matrix composites fabricated by friction stir processing

“…Threaded cylindrical and threaded tapered pins are proved to be able to produce homogeneously distributed composites. Plain cylindrical pins [31,42,43], square pins [29,44,45], conical pins [46] also have been successfully employed to produce AMCs. Under specific operating conditions for producing AA7075/SiC nano-composite, threaded tapered pin generated most uniform distribution of particles among triangular pin, square pin and four-flute square pin, whereas four-flute cylindrical pin could not produce proper material flow resulting in a large cluster of SiC [41].…”

“…When aluminum alloys are subjected to FSW/FSP, being a material with high stacking fault energy (γ SFE ≈ 160-200) [88], generally CDRX acts as main grain refining mechanism. Fine grains with more HAGBs are formed in the fabricated composites as a result of CDRX [35,43,45,51,61,89,90]. At the time of deformation of metal at elevated temperature, two opposite phenomena take place simultaneously, i.e., formation of dislocation and dynamic recovery, which determines the dislocation density in the material.…”

“…5b) which implies that the large quartz particles (32 µm) might have acted as nucleation sites rather than pinning the grain boundaries [86]. Both the pinning effects [42,45,70,[94][95][96][97][98] and PSN [45,92,94] have been reported as additional grain refinement mechanism for AMC fabrication. The grain refinement phenomenon intensifies with increasing fraction of reinforcement in the composite ( Fig.…”

“…All these microstructural behaviors enhance the tensile properties of the composites. A brittle IMC free strong interface between matrix and reinforcement helps in proper load transfer from matrix to particle/fiber [27,45,67,118,119]. The strong reinforcement can absorb more energy than the soft aluminum matrix, and consequently, the tensile strength is increased.…”