刘勤
,
夏锄
,
刘晓东
金属学报
在170,190,210,230,250℃的温度下,采用3.7×10~2,7.4×10~2和1.1×10~(-1)min(-1)的应变速率(平均)对Zn-5%Al共晶合金的m-C-δ(或m-k-δ)关系曲线(简称m-δ关系曲线)进行了测定.所有的曲线均随应变的δ增加而快速上升.俟达到某一定的应变量(极限应变量δ1)后。开始缓慢下降并保持平稳直至断裂.Zn-5%A1共晶合金的m-δ关系曲线不存在k_(?)=k_I(k_(I 1),k_(I 2),k_(I 3),……)=k_F(或C_0=C_I(C_(I 1),C_(I 2),C_(I 3),……)=C_F=1)的简单情况.可应用m-δ方程式[4,5]对曲线上各点C值(包括所有的C_I和C_F值)进行计算.C值随δ值的增加成近似的直线上升.直线的斜率在极限应变(δ1)处突然减小.
关键词:
Materials Letters
Secondary M,C precipitation was investigated in K40S cobalt-base alloy after 100 h aging at 950 degreesC. The results showed that it was closely related to the tungsten-rich zones inherited from the as-cast condition and the degeneration of the primary M7C3 carbide. A direct element reaction, 6M + C --> M6C, in which C comes from the decomposition of the M7C3 carbides, is suggested as the mechanism of secondary M6C precipitation in K40S alloy. (C) 2001 Elsevier Science B.V. All rights reserved.
关键词:
M6C precipitation;aging;M7C3 carbide;superalloy
胡标
,
尹明
,
王庆平
,
闵凡飞
,
杜勇
兵器材料科学与工程
基于文献报道的实验数据,采用相图计算(CALPHAD:CALculation of PHAse Diagrams)方法对V-M(M=Li,Na,K,Sc,Ag)5个二元系进行相图热力学研究.通过热力学优化计算获得了一套描述液相、(V)、(Li)、(Na)、(K)、(αSc)、(βSc)和(Ag)相的热力学参数.V-Li、V-Na和V-K体系中的气相视为由组元V、Li、Li2、Na、Na2、K和K2混合的理想气体.与实验相图数据对比表明,获得的热力学参数能够准确地描述实验相平衡数据.
关键词:
V-M(M=Li,Na,K,Sc,Ag)
,
CALPHAD方法
,
相图
,
热力学模型
Ying LI
材料科学技术（英文）
Oxide materials NaCo2O4 and (Na1-yMy)1.6Co2O4 (M=K, 0.05≤y≤0.35; M=Ca, Sr, 0.10≤y≤0.40) were prepared by a sol-gel method. Experimental results indicated that the Seebeck coefficient and the Power-factor of Na Co2O4 were improved by doping Ca and Sr but not by K. The Power-factor of NaCo2O4 is in its maximum, 1.68×10-4 W•m-1•K-2 and 11% bigger than that of the original one when the dopant fraction of Ca was 0.1. Doping Sr makes NaCo2O4 have the biggest Power-factor, 1.68×10-4 W•m-1•K-2 that is 50% bigger than the non-doping oxide. The experimental results indicate that suitable dopants and addition amounts could improve the thermoelectric properties of NaCo2O4 greatly.
关键词:
Thermoelectric materials
,
materials
,
Electric
,
proper
Xinbin HU
,
Mei ZHANG
,
Xiaochun WU
,
Lin LI
材料科学技术（英文）
Based on the local equilibrium assumption, coarsening behavior of M23C6 carbide at 700℃ in H13 steel was simulated by DICTRA software. The results from the calculations were compared with transmission electron microscopy (TEM) observations. The results show the interfacial energy for M23C6 in H13 steel at 700℃ is thus probably 0.7 J•m-2, which fits the experiments well. The influence of composition and temperature on the coarsening rate was also investigated by simulations. Simulations show a decrease in the coarsening rate when V/Mo ratio is increased, while the coarsening rate increases with increasing temperature.
关键词:
DICTRA Simulation
,
碳化物粗化
,
界面能
,
H13钢
Physica Status Solidi B-Basic Research
The high-order perturbation formulas of zero-field splitting D and gyromagnetic factors g(parallel to) and g(perpendicular to) for 3d(3) ions in tetragonal symmetry are established by using a two-spin-orbit(SO)-parameter model where the contributions to these EPR parameters from both the SO coupling of the central 3d(3) ions and that of the ligands are considered. From these formulas, the local structural parameters for the tetragonal V2+-V-M centers in MCl:V2+ (M = Na, K, Rb) crystals are estimated from the EPR data. The results are compared with those obtained from the conventional one-SO-parameter model where only the contribution of the SO coupling of central 3d(3) ions is included. The reasonableness of the results based on the two-SO-parameter model is discussed.
关键词:
ions
Radiation Effects and Defects in Solids
In this paper, we establish the high-order perturbation formulas of EPR zero-field splittings D, E and g factors, g(x), g(y) and g(z) for 3d(3) ions in a sort of rhombic symmetry where the symmetry axes and hence the crystal-field axes lie along the [001], [010] and [100] axes. From these formulas, the EPR parameters D, E, g(x), g(y) and g(z) for the rhombic Cr3+-V-M and Cr3+-Li+ defect centers in the tetragonal A(2)MF(4) (A = K, Rb, Cs; M = Mg, Zn, Cd) fluorides are calculated by considering the suitable defect-induced lattice distortions. The results are in reasonable agreement with the observed values.
关键词:
electron paramagnetic resonance;crystal-field theory;superposition;model;lattice distortions;Cr3+;A(2)MF(4) (A = K, Rb, Cs;M = Mg, Zn,;Cd;spin-orbit coupling;electron-paramagnetic-res;superposition model;cr-3+ centers;ions;rb2znf4;spectra;k2mgf4;k2znf4
