H.M. Geng
,
X.C. Wu
,
Y.A. Min
,
null
,
null
,
null
,
null
,
null
,
null
,
null
金属学报(英文版)
Experiments conducted to determine the effect of copper addition on the machinability of plastic mould steel 4Cr16Mo were presented. The machinability of mould steel 4Cr16Mo was improved obviously by adding Cu. The top wear of 4Cr16Mo with copper was less than that without copper. Cu-rich phase had the effect of lubricant and heat conductivity as solid lubricant, which reduced cutting-tool wear, improved machinability and increased service life of cutting-tool. With the increase of copper addition, the hot-working character of 4Cr16Mo decreased. The optimal hot-working parameters 4Cr16Mo with copper were determined by tensile test and compression test. The rate of deformation should be adopt as 0.6 s-1. The heating-up temperature, initial forging temperature and terminal forging temperature were 1200℃, 1150℃ and 950℃, respectively.
关键词:
machinability
,
cutting-tool
,
hot-shortness
李铂
,
周建江
,
夏伟杰
,
吴连慧
液晶与显示
doi:10.3788/YJYXS20142904.0605
直线是机载座舱显示画面中最基本的图元,其显示质量对于整个画面的显示效果影响较大,尤其是小角度下直线显示的“麻花”现象一直是影响显示效果的关键问题之一.为了提高小角度下直线的显示效果,本文提出了一种基于Wu算法的亮度渐变改进算法.该算法通过渐进地展现直线从轴方向上的亮度变化过程,减少亮度畸变,有效地改进了显示效果.通过Matlab仿真和FPGA实现,验证了该算法反走样后的小角度直线显示效果明显优于其他算法,而且结合中点画线法后,绘制时间与Wu算法相当.同时该算法还可改善大角度直线和圆弧的显示效果,消除了大角度直线的边缘锯齿,解决了圆弧在小角度部分的虚化问题.因此本文算法可用于对实时性和显示效果要求高的机载座舱显示系统,以缓解飞行员的视觉疲劳.
关键词:
座舱显示
,
反走样
,
改进Wu算法
,
小角度
,
FPGA实现
吴连慧
,
周建江
,
夏伟杰
,
陈雅雯
液晶与显示
doi:10.3788/YJYXS20153001.0163
对于光栅化的三角形,其边缘存在明显的锯齿现象,因此需要进行反走样处理.基于Wu直线反走样算法的思想,考虑了水平直线外侧直接添加插值点的算法和三角形三边外侧反走样的算法.综合两者的优点,在绘制光栅化的三角形的同时,边缘叠加Wu反走样直线,并考虑背景像素灰度值的作用.结果表明,改进的三角形光栅化的边缘反走样算法有效提高了三角形光栅化后边缘的显示效果,该算法计算量小,便于FPGA实现,可用于对图形显示质量要求很高的机载显示系统.
关键词:
反走样
,
Wu算法
,
光栅化
,
FPGA
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
