传统的3D打印技术逐渐无法满足高端制造领域对构件的要求,材料-结构-功能一体化增材制造即4D打印技术将是新的发展方向。为此,选取热塑性聚氨酯(TPU)/钕铁硼(NdFeB)磁性复合材料体系,采用激光选区烧结(Selective laser sintering,SLS)工艺成形具有不同Nd FeB含量的复合材料成形件,研究了复合粉末的粒度及其分布、微观形貌、成形前后化学基团演变,成形件晶体结构、力学性能及变形行为,结果表明Nd Fe B含量会影响复合材料成形件的力学性能和变形行为,增加Nd Fe B含量能够增大成形件在磁场中受到的作用力;当Nd Fe B含量在复合材料中质量分数为30%时,复合材料成形件拥有最佳的拉伸强度。本研究将TPU/NdFeB复合材料体系作为一种创新的4D打印材料,成形的磁性智能构件在磁场中发生变形,实现了磁场驱动的4D打印,对4D打印磁性智能构件的发展具有指导意义。
A new Ni-based superalloy Ni48Cr28W5Co3Mn1Si1.6 was developed and the influence of a trace amount of rare earth (RE) metal addition on the oxidation resistance of this alloy was investigated. Isothermal oxidation beha...
详细信息
A new Ni-based superalloy Ni48Cr28W5Co3Mn1Si1.6 was developed and the influence of a trace amount of rare earth (RE) metal addition on the oxidation resistance of this alloy was investigated. Isothermal oxidation behavior was investigated at 950?1150 °C in air, and then analyzed using scanning electronic microscopy and X-ray diffraction. The results showed that oxidation mass gain kinetics of the samples with and without RE elements follow the parabolic law. The effect of 0.20% RE on oxidation resistance is relatively small, and the oxidation rate constant of the alloy modified with 0.20% RE addition decreases by 5.9%?9.0%. Oxidation at 950?1150 °C for 100 h results in the formation of MnCr2O4, Cr2O3 and SiO2. A continuous and protective MnCr2O4 spinel layer forms as outer layer. The continuous middle oxide layer is confirmed to be Cr2O3, and the innermost layer consists of discontinuous SiO2.
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