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研究深冷轧制时效态纳米6061铝合金在100~500°C下等温热处理过程的晶粒生长。透射电子显微镜观察结果表明经深冷轧制及在130°C时效30 h,合金显微组织中含有61 nm的晶粒和50~150 nm的析出相,以及0.248%的点阵畸变。此外,由于形成细小的强化相和纳米晶粒,合金的拉伸强度达到362 MPa。在100~500°C下进行热稳定研究,结果表明,点阵畸变得到减弱,析出相溶解,晶粒长大。X射线衍射结果表明,当退火温度高于300°C时,Mg2Si相将消失。当退火温度低于200°C时,晶粒长大不明显,力学性能下降也不明显。但在300~500°C时,晶粒长大,析出相溶解和力学性能下降都比较明显。在100~200°C时,晶粒长大的活化能为203.3 k J/mol,在300~500°C时,活化能为166.34 k J/mol。讨论了析出相溶解对铝点阵常数和XRD(111)面峰位位移的影响,也讨论了PLC对应力应变曲线的影响。
The grain growth of 6061 aluminum alloy during cryogenic rolling at isothermal heat treatment at 100-500 ° C was studied. Transmission electron microscopy results show that the alloy microstructure contains 61 nm grains and 50-150 nm precipitates and 0.248% lattice distortion after cryogenic rolling and aging at 130 ° C for 30 h. In addition, the tensile strength of the alloy reached 362 MPa due to the formation of fine reinforced phase and nano-crystalline grains. Thermal stability at 100 ~ 500 ° C, the results show that the lattice distortion is weakened, precipitated phase dissolution, grain growth. X-ray diffraction results show that when the annealing temperature is higher than 300 ° C, Mg2Si phase will disappear. When the annealing temperature is below 200 ° C, the grain growth is not obvious, the mechanical properties decreased not obvious. However, at 300 ~ 500 ° C, grain growth, precipitated phase dissolution and mechanical properties are more obvious decline. The activation energy of grain growth is 203.3 kJ / mol at 100 ~ 200 ° C and 166.34 kJ / mol at 300 ~ 500 ° C. The effects of precipitation and dissolution on the lattice constant of aluminum and the peak position shift of XRD (111) surface are discussed. The effect of PLC on the stress-strain curve is also discussed.