X.C. Zhao
,
Y.D. Zhang
,
H.W.Zhang
金属学报(英文版)
A finite element model is developed for the
simulation of vibration stress relief (VSR) after welding. For the
nonresonant vibration, the reduction in stress strongly depends on
the amplitude of vibration. For the resonant vibration, the
vibration frequency is the key for stress relief. The vibration
frequency should be close to the structure natural frequency for the
desired vibration mode. Only small vibration amplitude is required,
which will be amplified during vibration. Vibration time does not
have a major impact on vibration stress relief. When the amplitude
of vibration stress relief is large, the treatment will be more
effective.
关键词:
Residual stress
,
null
,
null
Journal of Applied Physics
The effect of Co substitution on structure, phase transformation, and magnetic properties of R(16)Fe(76-x)Co(x)C(8) (R equivalent to Nd, Dy; 0 <= x <= 76) alloys prepared by a remilling process has been studied systematically. The process of remilling and subsequent annealing is more beneficial for the formation of Nd(2)(Fe,Co)(14)C compound in Nd(16)Fe(76-x)Co(x)C(8) alloys than in Dy(16)Fe(76-x)Co(x)C(8) alloys. The R(2)(Fe,Co)(14)C phase is obtained for Nd(16)Fe(76-x)Co(x)C(8) alloys with 0 <= x <= 20 and Dy(16)Fe(76-x)Co(x)C(8) alloys with 0 <= x <= 25. Higher Co content results in the formation of Nd(2)(Fe,Co)(17)C(delta)-type phase and Dy(Fe,Co)(7) phase for Nd(16)Fe(76-x)Co(x)C(8) and Dy(16)Fe(76-x)Co(x)C(8) alloys, respectively. The high coercivity, (i)H(c)=48.5 kOe, is achieved for Dy(16)Fe(51)Co(25)C(8) alloy. (C) 2008 American Institute of Physics.
关键词:
permanent-magnets;r2fe14c;carbides;carbon
吴松全
,
杨义
,
李阁平
,
平德海
,
胡青苗
,
杨锐
金属学报
doi:10.11900/0412.1961.2015.00309
针对体心立方(bcc)结构金属及合金{112}<111>孪生的ω点阵机制, 利用点阵模型详解了bcc结构金属及合金{112}<111>孪晶形核、长大和终止全过程. 模型揭示了孪晶可以通过ω→bcc转变过程形成孪晶核胚, 再通过孪晶核胚生长或合并的方式长大, 最终与特殊位向ω相作用受阻而停止. 该机制说明了{112}<111>类型孪晶是一种相变孪晶.
关键词:
金属和合金
,
孪晶
,
相变
,
ω点阵
Journal of Physical Chemistry C
The highly unusual structural and electronic properties of the alpha-phase of (Si(1-x)C(x))(3)N(4) are determined by density functional theory (DFT) calculations using the Generalized Gradient Approximation (GGA). The electronic properties of alpha-(Si(1-x)C(x))(3)N(4) are found to be very close to those of alpha-C(3)N(4). The bandgap of alpha-(Si(1-x)C(x))(3)N(4) significantly decreases as C atoms are substituted by Si atoms (in 2 most cases, smaller than that of either alpha-Si(3)N(4) or alpha-C(3)N(4)) and attains a minimum when the ratio of C to Si is close to 2. On the other hand, the bulk modulus of alpha-(Si(1-x)C(x))(3)N(4) is found to be closer to that of alpha-Si(3)N(4) than of alpha-C(3)N(4). Plasma-assisted synthesis experiments of CN(x) and SiCN films are performed to verify the accuracy of the DFT calculations. TEM measurements confirm the calculated lattice constants, and FT-IR/XPS analysis confirms the formation and lengths of C-N and Si-N bonds. The results of DFT calculations are also in a remarkable agreement with the experiments of other authors.
关键词:
chemical-vapor-deposition;silicon-carbon nitride;thin-films;optical-properties;room-temperature;alpha-phase;growth;hard;photoluminescence;microstructure
徐祖耀
金属学报
Fe-X-C系马氏体相变时的△G_(Fe-X-C)~(γ→α)为:△G_(Fe-X-C)~(γ→α)=_(xFe)△G_Fe~(γ→α)+_(XC)RT×ln_(γ_C~α/γ_C~γ)+x_i△G_i~(γ→α)+△Ω~(γ→α)其中γ_C~α和γ_C~γ分别表示碳在Fe-X-C系铁素体和奥氏体内的活度系数.对Fe-Ni-C和Fe-Cr-C系所求得的M_S值和实验值很好符合.碳在Fe-X-C系的活度值及对奥氏体的强化作用主要决定Fe-X-C系的M_s值.碳是决定Fe-X-C系相变驱动力的主要元素.
关键词:
张志力
,
周洋
,
艾明星
稀有金属材料与工程
采用Ti,Si,Al粉和石墨粉等元素作为主要原料,利用行星式球磨机,研究通过机械合金化法(MA)的反应球磨技术(RBM)活化烧结制备Ti3SiC2和Ti3A1C2粉末材料.通过X-射线衍射、扫描电镜等手段,分析研究了机械合金化过程中的元素组织结构变化和可能的机械化学反应.提出实验中机械合金化趋向于界面原子逐渐扩散的反应机制.
关键词:
机械合金化
,
三元碳化物
,
反应球磨
张志力
,
周洋
,
艾明星
稀有金属材料与工程
采用Ti,Si,Al粉和石墨粉等元素作为主要原料,利用行星式球磨机,研究通过机械合金化法(MA)的反应球磨技术(RBM)活化烧结制备Ti3SiC2和Ti3A1C2粉末材料.通过X-射线衍射、扫描电镜等手段,分析研究了机械合金化过程中的元素组织结构变化和可能的机械化学反应.提出实验中机械合金化趋向于界面原子逐渐扩散的反应机制.
关键词:
机械合金化
,
三元碳化物
,
反应球磨
