Al—Ti—C—B中间合金细化剂的研究

研究了新近开发的Ａｌ－Ｔｉ－Ｃ－Ｂ中间合金细化剂，检查了其显微组织及细化工业纯铝及含Ｚｒ铝合金的性能，并与Ａｌ－Ｔｉ－Ｂ中间合金细化剂进行了对比。结果表明，Ａｌ－Ｔｉ－Ｃ－Ｂ中间合金细化剂含有Ａｌ３Ｔｉ、ＴｉＢ２和ＴｉＣ三种第二相，经小弥散分布的多相粒子团，其细化工业纯铝晶粒的能力明显优于Ａｌ－Ｔｉ－Ｂ中间合金细化剂，并克服了Ａｌ－Ｔｉ－Ｂ中间合金细化易被Ｚｒ原子毒化的弱点，分析认为Ａｌ－Ｔｉ－Ｂ     

变形对中间合金细化剂组织及细化性能的影响

研究了挤压变形对铸态Ａｌ－Ｔｉ,Ａｌ－Ｔｉ－Ｂ和Ａｌ－Ｔｉ－Ｃ中间合金的微细胞及其细化性能的影响,变形引起铸态中间合金中的Ａｌ３Ｔｉ相断开,并使团簇状ＴｉＢ２和ＴｉＣ粒子趋于分散。变形使３种铸成中间合金的细化性有分别产生了不同的变化,初步探讨了原因。     

铸造Al—Si合金熔体处理——晶粒细化

对亚共晶Ａｌ－Ｓｉ铸造合金进行细化处理已成为一种基本操作,中间合金（Ａｌ－Ｔｉ,Ａｌ－Ｔｉ－Ｂ和Ａｌ－Ｂ合金）在亚共晶Ａｌ－Ｓｉ铸造合金中与在工业纯铝和变形铝合金中的晶粒细化行为存在较大的差异,Ａｌ－３Ｔｉ－３Ｂ,Ａｌ－３Ｂ中间合金在Ａｌ－Ｓｉ铸造合金中表现出优异的晶粒细胞化效应,Ｓｉ与晶粒细化剂的交互作用在其中扮演着重要的角色,通过炉前对熔体进行快速热分析可愉对晶粒细化效果和变质程度进行评价和预     

新一代铝合金晶粒细化剂Al-Ti-C

综述了新一代铝合金晶粒细化剂Ａｌ－Ｔｉ－Ｃ的理论研究情况。Ａｌ－Ｔｉ－Ｃ晶粒细化剂克服了Ａｌ－Ｔｉ－Ｂ的缺陷，其异质形核核心ＴｉＣ比ＴｉＢ２的聚集倾向更小，并对Ｚｒ、Ｃｒ、Ｖ、Ｍｎ等元素“中毒”免疫。在相同添加量时，Ａｌ－Ｔｉ－Ｃ细化效果优于Ａｌ－Ｔｉ－Ｂ，已成为取代Ａｌ－Ｔｉ－Ｂ的新一代晶粒细化剂。     

AlTiB中间合金细化行为的温度特性

研究了温度对 Ａｌ Ｔｉ Ｂ 中间合金细化效果的影响。试验结果表明， Ａｌ Ｔｉ Ｂ 中间合金的细化效果不仅取决于其本身的结构形态， 而且与细化工业纯铝的温度密切相关。比较了国内外三种 Ａｌ Ｔｉ Ｂ中间合金的细化效果随温度的变化规律， 发现， 其变化规律和达到最佳细化效果不同。     

铸造Al-Si合金熔体处理——晶粒细化

对亚共晶Ａｌ－Ｓｉ铸造合金进行细化处理已成为一种基本操作。中间合金（Ａｌ－Ｔｉ,Ａｌ－Ｔｉ－Ｂ和Ａｌ－Ｂ合金）在亚共晶Ａｌ－Ｓｉ铸造合金中与在工业纯铝和变形铝合金中的晶粒细化行为存在较大的差异。Ａｌ－３Ｔｉ－３Ｂ,Ａｌ－３Ｂ中间合金在Ａｌ－Ｓｉ铸造合金中表现出优异的晶粒细化效应,Ｓｉ与晶粒细化剂的交互作用在其中扮演着重要的角色。通过炉前对熔体进行快速热分析可以对晶粒细化效果和变质程度进行评价和预测,继而控制熔体处理的质量。对于亚共晶Ａｌ－Ｓｉ铸造合金,归纳起来有四种晶粒细化机理：包晶反应理论、共晶反应理论、硼化物颗粒理论和超形核理论。仅对Ａｌ－Ｓｉ铸造合金细化处理的最新进展、Ｓｉ与晶粒细化剂的交互作用和晶粒细化机理进行综合评述     

铝钛硼稀土中间合金的研制与生产

采用氟化物和过热铝液反应，并引入稀土元素，生产出新型的铝晶粒细化剂──Ａｌ－Ｔｉ－Ｂ－ＲＥ中间合金。该工艺具有产品质量稳定、生产效率高、能耗低、副产品可利用等特点。并采用连续铸轧法生产出Ａｌ－Ｔｉ－Ｂ－ＲＥ线状产品。本文还提出Ａｌ－Ｔｉ－Ｂ－ＲＥ是不同于Ａｌ－Ｔｉ－Ｂ的一种新型的铝晶粒细化剂，对Ａｌ－Ｔｉ－Ｂ－ＲＥ的细化效果及稀土的作用进行了阐述。     

Al-Ti-C中间合金细化剂的组织及其细化性能

以一析方法在低温、低搅拌条件下成功地制备了几种成分的Ａｌ－Ｔｉ－Ｃ中间合工采用Ｘ射线衍射（ＸＲＤ）,扫措电镜（ＳＥＭ）和能谱分析（ＥＤＳ）等手段对中间合金的相组成和显微组织进行了综合分析,结果表明,Ａｌ－Ｔｉ－Ｃ中间合中的第二相粒子为块状Ａｌ３Ｔｉ和亚微米尺寸的非整化合物ＴｉＣｘ,其中ｘ在０．４９～０．７８之间不等,细化结果表明。Ａｌ－Ｔｉ－Ｃ对工业纯铝具有良好的晶粒细化效果,细化的闰核心为Ｔｉ,     

AlTiC和Al4B、Al3Ti4B中间合金对纯铝和亚共晶铝硅合金的细化机理

研究了ＡＩＴｉＣ和ＡＩ４Ｂ、ＡＩ３Ｔｉ４Ｂ等中间合金细化剂对纯铝和亚共晶铝硅合金的细化效果和细化机理。实现发现ＡＩ６Ｔｉ０．２Ｃ对纯铝有很好的细化效果,但对高Ｓｉ含量的亚共晶铝硅合金几乎没有细化效果;而ＡＩ４Ｂ、ＡＩ３Ｔｉ４Ｂ等ｗ（Ｔｉ）／ｗ（Ｂ）〈２．２（ｗ（Ｔｉ）／ｗ（Ｂ）＝０时即为ＡＩ－Ｂ合金）的ＡＩＴｉＢ合金对纯铝没有细化效果,但对亚共晶铝硅合金却有非常好的细化效果。上述实验结果与中间合金的成分及其第二相的类型有直接关系,即与不同中间合金的细化机理相关。     

杆状AlTiB中间合金的组织形貌及晶粒细化行为的研究

杆状ＡｌＴｉＢ中间合金是铝及其合金连铸过程中最常用的晶粒细化剂。本文采用Ｘ射线衍射和晶粒细化对比试验对国内外杆状ＡｌＴｉＢ中间合金进行了全面分析，发现它们的组成相均为α－Ａｌ＋ＴｉＡｌ３＋ＴｉＢ２。但国内产品的钛含量及ＴｉＢ２、ＴｉＡｌ３相含量偏低，晶粒细化效果很差。自行研制的ＡｌＴｉＢ中间合金的钛含量和ＴｉＢ２、ＴｉＡｌ３相含量与国外产品相当，晶粒细化效果也可与之媲美。探讨了ＡｌＴｉＢ中间合金在铝及铝合金中的形核机理。     

The disconnection mechanism of coupled migration and shear at grain boundaries

The mechanism of coupled migration and shear is studied in a range of [0 0 0 1] tilt boundaries in hexagonal close-packed metal using atomic-scale computer simulation. Symmetrical tilt boundaries spanning the low- and high-angle regimes and comprising regular arrays of grain boundary dislocations are simulated. For each misorientation, θ, the perfect boundary (pristine) is investigated as well as one containing a disconnection. Both types of structures are subjected to incremental applied strains to determine the stress that produces coupled migration and shear. The stress for motion in the pristine case, entailing nucleation, is higher than the Peierls stress for motion when disconnections are present. We conclude that the applied stresses in our simulations exert a Peach-Koehler force on pre-existing disconnections, thereby providing a feasible mechanism with a well-defined driving force that produces coupled migration and shear. This mechanism is feasible for the lower-angle boundaries studied, and facile for the high-angle cases.     

Mobility of Σ5 tilt grain boundaries: Inclination dependence

Molecular dynamics simulations were performed to examine the influence of grain boundary inclination on the stress-driven motion of flat <0 1 0> Σ5 tilt asymmetric of different inclinations in Ni. The inclination dependence of the mobility, boundary diffusivity and energy are correlated. Special properties are associated with low index boundary planes.     

PS版电解粗化条件对砂目参数的影响规律

通过模拟电解磨版的工业化生产条件,研究了在盐酸电解体系下电解磨版条件对砂目参数的影响规律。盐酸的浓度在0.008~0.016 g/ml的范围内,高度方面的砂目参数(Ra、Rz、Rq)随着盐酸浓度的升高均呈下降的趋势,而Rt、Ry、Sm(间距参数)先呈下降趋势,到盐酸浓度为0.014 g/ml时开始变为上升趋势;随着温度的升高,Ra、Rz、Rt、Rq、Ry、Sm都呈上升的趋势,并且会使砂目分布趋于均匀;随着电流密度的增大,Ra、Rz、Ry均呈上升趋势,Rt、Rq基本保持不变,Sm有一个峰值;随着电量密度的增加,Ra、Rz、Rt、Rq、Ry、Sm都呈上升的趋势。     

Computation of Five-Dimensional Grain Boundary Energy

A broken-bond type computational method has been developed for the calculation of the five-dimensional grain boundary energy. The model allows quick quantification of the unrelaxed five-dimensionally specified grain boundary energy in arbitrary orientations. It has been validated on some face-centred cubic metals. The stereo projections of grain boundary energy of ∑3,∑5,∑7,∑9,∑11,∑17 b and ∑31a have been studied. The results of Ni closely resemble experimentally determined grain boundary energy distribution figures, suggesting that the overall anisotropy of grain boundary energy can be reasonably approximated by the present simple model. Owing to the overlooking of relaxation matter, the absolute values of energy calculated in present model are found to be higher than molecular dynamic-based results by a consistent magnitude, which is 1 J/m2 for Ni. The coverage of present method forms a bridge between atomistic and meso-scale simulations regarding polycrystalline microstructure.     

Grain boundary migration and grain rotation studied by molecular dynamics

We report on molecular dynamics simulations of an isolated cylindrical grain in copper shrinking under capillary forces. At low temperatures, the coupling between grain boundary (GB) migration and grain translation induces rotation of the grain towards higher or lower misorientation angles, depending on the initial misorientation. The dynamics of the GB motion and grain rotation are studied as functions of the initial misorientation angle and temperature. The effects of imposed constraints blocking the grain rotation or exerting a cyclic torque are examined. The simulation results verify several predictions of the model proposed by Cahn and Taylor [Acta Mater 52, 4887 (2004)]. They also indicate that the GB motion is never perfectly coupled but instead involves at least some amount of sliding. This, in turn, requires continual changes (annihilation or nucleation) in the GB dislocation content. Dislocation mechanisms that can be responsible for the motion of curved GBs and dislocation annihilation in them are proposed.