The effects of composite rare earths La+Ce on properties of CuZnAl shape memory alloys were studied bymetallograph examination, tensile and bending tests, electric resistivity measurements, EDS and SEM. The test resul...The effects of composite rare earths La+Ce on properties of CuZnAl shape memory alloys were studied bymetallograph examination, tensile and bending tests, electric resistivity measurements, EDS and SEM. The test resultsshow that the grain size of CuZnAl shape memory alloys could be diminished effectively and the mechanical propertiesimproved obviously by the addition of composite rare earths La+Ce (La: Ce=1: 1). Meanwhile, the excellent shapememory properties remained unchanged. The results of microanalyses indicate that the composite rare earths were segregated at grain boundaries and impeded the grain growth, leading to the improvement of the mechanical properties ofCuZnAl alloys. If the amount of composite rare earths La+Ce was greater than 0. 10%, the shape memorial propertiesbecame poor.展开更多
Effect of compound rare earth (RE) on shape memory effect (SME) of Fe-Mn-Si-Ni-C shape memory alloy was studied by bent measurement,thermal cycle training, SEM and XRD etc. The results show that metallurgic microstruc...Effect of compound rare earth (RE) on shape memory effect (SME) of Fe-Mn-Si-Ni-C shape memory alloy was studied by bent measurement,thermal cycle training, SEM and XRD etc. The results show that metallurgic microstructure is refined and SME improved evidently with the addition of compound RE. The alloy appears little two-way shape memory effect. The former training and addition of compound RE are two effective ways to restrain martensitic stability. XRD analysis also indicates that ε→γ reversible transition ratio increases by training greatly help to improve SME of the alloy.展开更多
Martensitic transformations, martensitic structures and substructures of Ni50Mn29Ga21Tb1.2 shape memory alloy were studied by DTA, X-ray diffraction and electron diffraction. The results show that the mainly phase at...Martensitic transformations, martensitic structures and substructures of Ni50Mn29Ga21Tb1.2 shape memory alloy were studied by DTA, X-ray diffraction and electron diffraction. The results show that the mainly phase at room temperature has body-centred tetragonal structure with the lattice parameters ： a = b = 0.60 ran, c = 0.5546 nm; and has body-centred monoclinic with lattice parameters： a =0.616 nm, b =0.581 nm, c = 0.553 nm, β = 90.8° in some tiny area. The substructures of Ni50Mn29Ga21Tb1.2 at room temperature are twin.展开更多
Improving the up-conversion luminescence efficiency crucial in several related application areas. In this work, of rare-earth ions via the multi-photon absorption process is we theoretically propose a feasible scheme ...Improving the up-conversion luminescence efficiency crucial in several related application areas. In this work, of rare-earth ions via the multi-photon absorption process is we theoretically propose a feasible scheme to enhance the resonance-mediated two-photon absorption in Er3＋ ions by shaping the femtosecond laser field with a rectangle phase modulation. Our theoretical results show that the resonance-mediated two-photon absorption can be decomposed into the on-resonant and near-resonant parts, and the on-resonant part mainly comes from the contribution of laser central frequency components, while the near-resonant part mainly results from the excitation of low and high laser frequency components. So, the rectangle phase modulation can induce a constructive interference between the two parts by properly designing the modulation depth and width, and finally realizes the resonance-mediated two-photon absorption enhancement. More- over, our results also show that the enhancement efficiency of resonance-mediated two-photon absorption depends on the laser pulse width （or laser spectral bandwidth）, final state transition frequency, and intermediate and final state absorption bandwidths. The enhancement efficiency modulation can be attributed to the relative weight manipulation of on-resonant and near-resonant two-photon absorption in the whole excitation process. This study presents a clear physical insight for the quantum control of resonance-mediated two-photon absorption in the rare-earth ions, and there will be an important significance for improving the up-conversion luminescence efficiency of rare-earth ions.展开更多
文摘The effects of composite rare earths La+Ce on properties of CuZnAl shape memory alloys were studied bymetallograph examination, tensile and bending tests, electric resistivity measurements, EDS and SEM. The test resultsshow that the grain size of CuZnAl shape memory alloys could be diminished effectively and the mechanical propertiesimproved obviously by the addition of composite rare earths La+Ce (La: Ce=1: 1). Meanwhile, the excellent shapememory properties remained unchanged. The results of microanalyses indicate that the composite rare earths were segregated at grain boundaries and impeded the grain growth, leading to the improvement of the mechanical properties ofCuZnAl alloys. If the amount of composite rare earths La+Ce was greater than 0. 10%, the shape memorial propertiesbecame poor.
文摘Effect of compound rare earth (RE) on shape memory effect (SME) of Fe-Mn-Si-Ni-C shape memory alloy was studied by bent measurement,thermal cycle training, SEM and XRD etc. The results show that metallurgic microstructure is refined and SME improved evidently with the addition of compound RE. The alloy appears little two-way shape memory effect. The former training and addition of compound RE are two effective ways to restrain martensitic stability. XRD analysis also indicates that ε→γ reversible transition ratio increases by training greatly help to improve SME of the alloy.
文摘Martensitic transformations, martensitic structures and substructures of Ni50Mn29Ga21Tb1.2 shape memory alloy were studied by DTA, X-ray diffraction and electron diffraction. The results show that the mainly phase at room temperature has body-centred tetragonal structure with the lattice parameters ： a = b = 0.60 ran, c = 0.5546 nm; and has body-centred monoclinic with lattice parameters： a =0.616 nm, b =0.581 nm, c = 0.553 nm, β = 90.8° in some tiny area. The substructures of Ni50Mn29Ga21Tb1.2 at room temperature are twin.
基金Project supported by the National Natural Science Foundation of China(Grant No.11474096)the Science and Technology Commission of Shanghai Municipality,China(Grant Nos.14JC1401500,17ZR146900,and 16520721200)the Higher Education Key Program of He'nan Province of China(Grant No.17A140025)
文摘Improving the up-conversion luminescence efficiency crucial in several related application areas. In this work, of rare-earth ions via the multi-photon absorption process is we theoretically propose a feasible scheme to enhance the resonance-mediated two-photon absorption in Er3＋ ions by shaping the femtosecond laser field with a rectangle phase modulation. Our theoretical results show that the resonance-mediated two-photon absorption can be decomposed into the on-resonant and near-resonant parts, and the on-resonant part mainly comes from the contribution of laser central frequency components, while the near-resonant part mainly results from the excitation of low and high laser frequency components. So, the rectangle phase modulation can induce a constructive interference between the two parts by properly designing the modulation depth and width, and finally realizes the resonance-mediated two-photon absorption enhancement. More- over, our results also show that the enhancement efficiency of resonance-mediated two-photon absorption depends on the laser pulse width （or laser spectral bandwidth）, final state transition frequency, and intermediate and final state absorption bandwidths. The enhancement efficiency modulation can be attributed to the relative weight manipulation of on-resonant and near-resonant two-photon absorption in the whole excitation process. This study presents a clear physical insight for the quantum control of resonance-mediated two-photon absorption in the rare-earth ions, and there will be an important significance for improving the up-conversion luminescence efficiency of rare-earth ions.
