Subjects: Materials Science >> Materials Science (General) submitted time 2023-03-31 Cooperative journals: 《材料研究学报》
Abstract： The W fiber/Zr-based metallic glass composite was prepared by infiltration and rapid solidification. The effect of the ratios of length to diameter of fibers on the compressive properties of the composite was investigated in detail. The results show that the yield strength firstly decreases with the increase of the length to diameter ratio then reaches a stable value when the ratio is greater than 1. The plastic strain has no obvious change when the ratio is greater than or equal to 1.25, while the plastic strain is bigger than 50% when the ratio is smaller than 1.25. The reason for these phenomena is the comprehensive effect of the friction force between pressure head and the end of the compressive sample, the change of the length to diameter ratio of the metallic glass fibers between W fibers and the mismatching between metallic glass matrix and the W fiber during deformation.
Subjects: Materials Science >> Materials Science (General) submitted time 2023-03-19 Cooperative journals: 《金属学报》
Abstract： Annealed 7B04 Al sheets in thickness of 2 mm were subjected to friction stir welding (FSW) under three rotation rate and welding speed parameters of 1600 r/min, 200 mm/min; 800 r/min, 200 mm/min and 400 r/min, 400 mm/min, respectively. The effect of welding parameters on the tensile property and microstructure of the FSW joints were investigated, with more efforts focusing on the low-temperature superplasticity of the nugget zones (NZs). The results showed that FSW joints with high quality could be produced by controlling welding parameters, with a joint strength coefficient of 100% being obtained. Dynamic recrystallization took place in the NZs with fine and equiaxed grains generated. The grain size of the base material was about 300 μm, while it was significantly decreased in the NZs with decreasing the rotation rate: about 2, 1 and 0.6 μm for the above three samples, respectively. The fine grain structure of the NZs could facilitate their superplastic deformation. The NZs exhibited superplastic elongations ranged from 160% to 590% at 300 ℃ at strain rates of 1×10-3 and 3×10-4 s-1. The maximum superplasticity of 790% was obtained at 350 ℃ at the strain rate of 1×10-3 s-1. The ability to superplastic deformation disappeared in the NZs at 400 ℃.
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