中国科学院云南天文台首次提出了太阳爆发过程及相应磁场结构抵近探测的科学项目,该项目将对太阳大气及发生在其中的剧烈活动进行前所未有的近距离测量。为项目研制的探测器近日区域运行时间将超过帕克太阳探测器(Parker Solar Probe,P...中国科学院云南天文台首次提出了太阳爆发过程及相应磁场结构抵近探测的科学项目,该项目将对太阳大气及发生在其中的剧烈活动进行前所未有的近距离测量。为项目研制的探测器近日区域运行时间将超过帕克太阳探测器(Parker Solar Probe,PSP)和太阳轨道探测器(Solar Orbiter),其热防护系统遇到的困难也远超后两者。首先分析了抵近探测器的轨道环境特点,提出了热防护的设计思路,然后给出了具体热防护系统设计、仿真和地面实验方案。初步研究显示,热防护系统的设计方案具有辐射散热好、耐高温、稳定可靠等优点。展开更多
高温高压相图在物理化学、矿物学、地球科学和极端条件下的材料科学中都具有重要的地位和应用价值,相图计算方法(alculation of phase diagram,CALPHAD)是建立温度-压强热力学相图和热力学数据库的主要方法,可以计算材料体系的相平衡、...高温高压相图在物理化学、矿物学、地球科学和极端条件下的材料科学中都具有重要的地位和应用价值,相图计算方法(alculation of phase diagram,CALPHAD)是建立温度-压强热力学相图和热力学数据库的主要方法,可以计算材料体系的相平衡、组成相的相分数和相成分、热力学性质,一定程度上解决单一实验建立高温高压相图的困难。本文对基于CALPHAD的高温高压相图建模方法进行了详细介绍,并总结其当前面临的问题和下一步研究方向,为极端条件下材料设计和性能评估奠定基础。展开更多
The stability, electronic structures, and mechanical properties of the Fe-Mn-Al system were determined by firstprinciples calculations. The formation enthalpy and cohesive energy of these Fe-Mn-Al alloys are negative ...The stability, electronic structures, and mechanical properties of the Fe-Mn-Al system were determined by firstprinciples calculations. The formation enthalpy and cohesive energy of these Fe-Mn-Al alloys are negative and show that the alloys are thermodynamically stable. Fe3Al, with the lowest formation enthalpy, is the most stable compound in the Fe-Mn-Al system. The partial density of states, total density of states, and electron density distribution maps of the Fe-Mn-Al alloys were analyzed. The bonding characteristics of these Fe-Mn-Al alloys are mainly combinations of covalent bonding and metallic bonds. The stress-strain method and Voigt-Reuss-Hill approximation were used to calculate the elastic constants and moduli, respectively. Fe2.5Mn0.5Al has the highest bulk modulus, 234.5 GPa. Fel.sMn1.5Al has the highest shear modulus and Young＇s modulus, with values of 98.8 GPa and 259.2 GPa, respectively. These Fe-Mn-Al alloys display disparate anisotropies due to the calculated different shape of the three-dimensional curved surface of the Young＇s modulus and anisotropic index. Moreover, the anisotropic sound velocities and Debye temperatures of these Fe-Mn-Al alloys were explored.展开更多
The thermodynamic stabilities, electronic structures, and mechanical properties of the Pd-based superalloys are studied by first principles calculations. In this work, we discuss the effect of Pd-based superalloys mad...The thermodynamic stabilities, electronic structures, and mechanical properties of the Pd-based superalloys are studied by first principles calculations. In this work, we discuss the effect of Pd-based superalloys made from Al, Si, Sc, Ti, V, Cr, Mn, Fe, Cu, Zn, Y, Zr, Nb, Mo, Tc, Hf, Ta, W, Re, Os, Ir and Pt, and we also calculate a face centered cubic （fcc） structure 222 superalloy including 31 Pd atoms and one alloying element TM （Pd31TM）. The mixing energies of these Pd-Based superalloys are negative, indicating that all Pd-based superalloys are thermodynamically stable. The Pd31Mn has the lowest mixing energy with a value of-0.97 eV/atom. The electronic structures of the Pd-based superalloys are also studied, the densities of states, elastic constants and moduli of the mechanical properties of the Pd-based superalloys are determined by the stress-strain method and Voigt-Reuss-Hill approximation. It is found that Pd31TM is mechanically stable, and Pd31Tc has the largest C11, with a value 279.7 GPa. The Pd31Cr has the highest bulk modulus with a value of 299.8 GPa. The Pd31Fe has the largest shear modulus and Youngs modulus with the values of 73.8 GPa and 195.2 GPa, respectively. By using the anisotropic index, the anisotropic mechanical properties of the Pd31TM are discussed, and three-dimensional （3D） surface contours and the planar projections on （001） and （110） planes are also investigated by the Young modulus.展开更多
文摘中国科学院云南天文台首次提出了太阳爆发过程及相应磁场结构抵近探测的科学项目,该项目将对太阳大气及发生在其中的剧烈活动进行前所未有的近距离测量。为项目研制的探测器近日区域运行时间将超过帕克太阳探测器(Parker Solar Probe,PSP)和太阳轨道探测器(Solar Orbiter),其热防护系统遇到的困难也远超后两者。首先分析了抵近探测器的轨道环境特点,提出了热防护的设计思路,然后给出了具体热防护系统设计、仿真和地面实验方案。初步研究显示,热防护系统的设计方案具有辐射散热好、耐高温、稳定可靠等优点。
基金the financial support from the Rare and Precious Metals Material Genetic Engineering Project of Yunnan Province,China(Nos.202102AB080019-1,202002AB080001-1)the Yunnan Fundamental Research Projects,China(Nos.202101AW070011,202101BE070001-015)the Youth Project of Yunnan Basic Research Program,China(No.202001AU070033)。
文摘高温高压相图在物理化学、矿物学、地球科学和极端条件下的材料科学中都具有重要的地位和应用价值,相图计算方法(alculation of phase diagram,CALPHAD)是建立温度-压强热力学相图和热力学数据库的主要方法,可以计算材料体系的相平衡、组成相的相分数和相成分、热力学性质,一定程度上解决单一实验建立高温高压相图的困难。本文对基于CALPHAD的高温高压相图建模方法进行了详细介绍,并总结其当前面临的问题和下一步研究方向,为极端条件下材料设计和性能评估奠定基础。
基金Project supported by the National Natural Science Foundation of China(Grant No.51261013)
文摘The stability, electronic structures, and mechanical properties of the Fe-Mn-Al system were determined by firstprinciples calculations. The formation enthalpy and cohesive energy of these Fe-Mn-Al alloys are negative and show that the alloys are thermodynamically stable. Fe3Al, with the lowest formation enthalpy, is the most stable compound in the Fe-Mn-Al system. The partial density of states, total density of states, and electron density distribution maps of the Fe-Mn-Al alloys were analyzed. The bonding characteristics of these Fe-Mn-Al alloys are mainly combinations of covalent bonding and metallic bonds. The stress-strain method and Voigt-Reuss-Hill approximation were used to calculate the elastic constants and moduli, respectively. Fe2.5Mn0.5Al has the highest bulk modulus, 234.5 GPa. Fel.sMn1.5Al has the highest shear modulus and Young＇s modulus, with values of 98.8 GPa and 259.2 GPa, respectively. These Fe-Mn-Al alloys display disparate anisotropies due to the calculated different shape of the three-dimensional curved surface of the Young＇s modulus and anisotropic index. Moreover, the anisotropic sound velocities and Debye temperatures of these Fe-Mn-Al alloys were explored.
基金Project supported by the Young-Talent Support Programs of Kunming University of Science and Technology,China(Grant No.11504146)the National Natural Science Foundation of China(Grant No.51762028)
文摘The thermodynamic stabilities, electronic structures, and mechanical properties of the Pd-based superalloys are studied by first principles calculations. In this work, we discuss the effect of Pd-based superalloys made from Al, Si, Sc, Ti, V, Cr, Mn, Fe, Cu, Zn, Y, Zr, Nb, Mo, Tc, Hf, Ta, W, Re, Os, Ir and Pt, and we also calculate a face centered cubic （fcc） structure 222 superalloy including 31 Pd atoms and one alloying element TM （Pd31TM）. The mixing energies of these Pd-Based superalloys are negative, indicating that all Pd-based superalloys are thermodynamically stable. The Pd31Mn has the lowest mixing energy with a value of-0.97 eV/atom. The electronic structures of the Pd-based superalloys are also studied, the densities of states, elastic constants and moduli of the mechanical properties of the Pd-based superalloys are determined by the stress-strain method and Voigt-Reuss-Hill approximation. It is found that Pd31TM is mechanically stable, and Pd31Tc has the largest C11, with a value 279.7 GPa. The Pd31Cr has the highest bulk modulus with a value of 299.8 GPa. The Pd31Fe has the largest shear modulus and Youngs modulus with the values of 73.8 GPa and 195.2 GPa, respectively. By using the anisotropic index, the anisotropic mechanical properties of the Pd31TM are discussed, and three-dimensional （3D） surface contours and the planar projections on （001） and （110） planes are also investigated by the Young modulus.
