取向硅钢中AlN析出的动力学

利用理论计算方法系统地计算和分析了取向硅钢中AlN在不同的形核机制下的析出动力学特征,如临界形核半径、临界形核功、相对形核率以及时间-温度-析出(TTP)曲线。计算结果显示,AlN在均匀形核、晶界形核或位错形核时临界形核尺寸不变。晶界形核时,AlN的临界形核功最小,相对形核率最大,AlN沉淀析出TTP曲线鼻子点温度为1 020℃,AlN沉淀析出的形核机制主要为晶界形核。     

微合金化钢中碳化铌在铁素体中的沉淀

对铌含量分别为0.24、0.15和0.08％的三炉微合金化钢中碳化铌在铁素体中的沉淀进行了较为深入的研究。利用有关理论估算出碳化铌在铁素体中均匀沉淀时的沉淀粒子形状、临界核心尺寸、均匀形核率、最大形核率温度和沉淀完成时间,试验结果与理论计算结果很好地符合。由此而得的结论无论在理论方面还是在实际生产应用方面都具有重要的意义。     

取向硅钢奥氏体中AlN沉淀析出的动力学计算

利用第二相沉淀析出的理论计算了取向硅钢奥氏体中AlN沉淀析出的动力学,结果表明:AlN在奥氏体中不同形核机制的临界形核尺寸相同,且临界形核尺寸随着温度的升高而增加。AlN在晶界形核的临界形核功最小,相对形核率最大,开始析出时间最短。虽然均匀形核和位错形核的临界形核功相当,但是AlN均匀形核的相对形核率比位错形核大2～3个数量级,均匀形核的开始析出时间也比位错形核短,奥氏体中AlN的主要形核机制是晶界形核。     

3%取向硅钢中MnS沉淀析出动力学的计算

利用第二相相关理论计算分析薄板坯连铸连轧3%取向硅钢中MnS沉淀析出的动力学行为。沉淀析出计算结果显示在薄板坯连铸连轧生产工艺中以铁素体位错线上形核为主导,MnS在铁素体中的析出量最大,其有效沉淀温度范围约为700~900℃,临界形核尺寸约为0.7~1.5 nm;相变完成时MnS颗粒的半径约为30 nm,可以起到抑制剂的作用。终轧温度应在800℃以上。     

汽车大梁钢中第二相粒子析出行为

运用热动力学理论和Oswald熟化理论研究了不同氮含量汽车大梁钢中第二相粒子的析出和熟化行为.研究发现钢中N含量的增加会促进V(C,N)在奥氏体中析出从而细化铁素体晶粒,当氮的质量分数增至4.2×10-4时铁素体晶粒尺寸能细化至4.7μm.形核率–温度曲线和析出–温度–时间曲线表明氮含量的增加可以扩大奥氏体区中最大形核率的温度范围,氮的质量分数由5.5×10-5增至4.2×10-4时其最快析出的鼻点温度由840℃上升至968℃.透射电镜观察显示氮含量的增加明显降低析出V(C,N)粒子的尺寸.VN在奥氏体中的Oswald熟化速率计算表明熟化速率随温度的降低不断减少,同时增加N含量还可以有效降低析出粒子的熟化速率,从而抑制沉淀析出的第二相粒子的熟化长大过程.      

微合金钢中微合金碳氮化物在奥氏体中的沉淀问题

微合金碳氮化物在奥氏体中的沉淀析出行为将对形变奥氏体的再结晶行为、奥氏体晶粒粗化行为以及在一定程度上对钢的沉淀强化行为产生显著的影响。本文探讨了微合金钢中M(CN)相析出的热力学、形核长大动力学、M(CN)相析出与晶体缺陷关系等重要基本理论问题,进行了系统的试验研究和     

镍对Fe-Cu-Ni合金中铜析出行为的影响

 利用透射电子显微镜(TEM)对Fe-Cu和Fe-Cu-Ni合金中铜颗粒的析出形貌及成分进行观察。同时根据Cahn-Hilliard非经典形核理论和Modified Langer Schwartz模型对合金中沉淀的析出过程进行模拟计算。扫描透射电镜(STEM)试验结果表明,镍元素在沉淀核心处浓度很低,而在颗粒-基体界面处存在富集现象,添加元素镍可降低沉淀颗粒的形核功,促进沉淀析出和长大粗化。该试验结果与理论模型预测结果一致。     

锆夹杂物对钢中铜元素非均质形核作用的理论分析

为了研究钢中铜元素非均质形核析出从而减轻钢中铜元素晶界偏聚的问题,选取钢中锆夹杂物作为形核质点,对试验钢中Zr O2、Zr C、Zr N析出学条件进行了热力学计算,通过点阵错配度理论和经验电子理论对钢中铜元素与锆夹杂物之间的非均质形核能力的大小进行了理论计算。结果表明,铜与Zr O2、Zr C、Zr N的点阵错配度分别为1.17%、9.53%、11.71%,经验电子理论特征参量分别为1.906、1.124 5、1.070。形核相和形核质点之间错配度越小,特征参量越大,非均质形核能力越强,经验电子理论计算结果与点阵错配度计算结果一致,Zr O2为最有效非均质形核质点,Zr C和Zr N为中等有效非均质形核质点,两种方法计算结果说明钢中锆的夹杂物可以作为铜元素的形核质点。     

Monte Carlo再结晶形核模拟新模型

基于金属再结晶形核理论和实验基础,对现有再结晶Monte Carlo模拟形核模型进行改进,建立新的再结晶形核模拟新模型,并将之应用于高纯铝冷轧后等温退火过程模拟.结果表明,新模型有效地模拟了再结晶非均匀形核过程,模拟的形核顺序、形核率曲线与再结晶理论、实验结果一致.     

X80管线钢微孔洞形核

利用扫描电镜和透射电镜等手段,观察了X80管线钢中的夹杂物和MA岛,获得了它们的尺寸统计特征.应用不同颈缩程度的拉伸试验,探明了X80管线钢中微孔洞萌生的机理:第一阶段微孔洞的形核是围绕钙处理夹杂物,在颈缩初期已经开始;第二阶段属高应变量阶段,此时孔洞是通过MA岛/基体界面脱离形核.通过有限元法分析了拉伸过程,确定了试样的真实应力-应变曲线,计算了钙处理夹杂物/基体界面强度和MA岛/基体界面强度.      

Refined Energy Correction for Calibration of Submerged Radial Gates

The energy-momentum (E-M) method for calibrating submerged radial gates was refined using a large laboratory data set collected at the Bureau of Reclamation hydraulics laboratory in the 1970s. The original E-M method was accurate in free flow, and when the gate significantly controls submerged flow, but for large gate openings with low head loss through the gate, discharge prediction errors were sometimes large (approaching 70%). Several empirical factors were investigated with the laboratory data, including the combined upstream energy loss and velocity distribution factor and the submerged flow energy correction. The utility of the existing upstream energy loss and velocity distribution factor relation was extended to larger Reynolds numbers. The relation between the relative energy correction and the relative submergence of the vena contracta was shown to be sensitive to the relative jet thickness. A refined energy correction model was developed, which significantly improved the accuracy of submerged flow discharge predictions. Although the focus of this work was radial gates, the energy correction concept and these refinements potentially have application to all submerged sluice gates.     

Distinguishing depressed from nondepressed individuals using energy and psychosocial variables.

This study was conducted to determine whether energy level can be used to distinguish depressed from nondepressed individuals and to assess the relative importance of energy level and psychosocial variables in making this distinction. Fifty-seven participants experiencing a current episode of major depression and a matched sample of nondepressed participants completed a self-report questionnaire containing measures of energy level and psychosocial variables. Discriminant analysis revealed that energy level correctly classified 93% as depressed or nondepressed, whereas psychosocial variables correctly classified 87%. Combining the energy and psychosocial variables did not increase the accuracy of classification over that achieved by using only the energy measures. The measure of exhaustion provided the greatest relative contribution to the overall discriminant function. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Radiation physics and radiobiology

Three quite general rules link radiation physics to radiobiology. They concern the dependence on linear energy transfer of relative biological effectiveness and of the cross section for cell killing, as well as the dependence of relative biological effectiveness on absorbed dose. These rules are accounted for in compound dual radiation action according to which damage in the nanometer domain depends linearly on dose with no dose rate dependence and on relative biological effectiveness that is limited to low values because of saturation. Energy concentration in the micrometer domain can cause large relative biological effectiveness in processes in which pairs of DNA lesions interact with quadratic dose dependence and dose rate dependence for low linear energy transfer radiations. Damage at both the nanometer and the micrometer level can cause observed effects and their relative contributions determine the maximum relative biological effectiveness at very low doses.     

Protein and energy metabolism in two lines of chickens selected for growth on high or low protein diets

Genetic adaptation was investigated in broilers selected for seven generations on a normal (A) or a low (B) protein diet. Protein and energy metabolism were studied in males from these selected lines fed on a diet of intermediate protein content. All selected birds retained more nitrogen than those studied 10 years previously. There was no difference in nitrogen retention between groups, although relative growth rate of group B birds was higher. Heat productions relative to gross energy intake were 0.38 (group B) and 0.45 (group A). Energy retentions relative to gross energy intake were 0.39 (group B) and 0.35 (group A); the difference being primarily due to higher fat retention in group B. Using a common maintenance requirement for metabolisable energy, group B utilised metabolisable energy for growth (0.78) better than did group A (0.71). At 53 d of age plasma glucose (10%) and insulin (50%) were higher in group B than in group A.     

Energy Dissipation on Submerged Block Ramps

Block ramps represent structures that produce high energy dissipation and have a unique characteristic of preserving the ecological balance in a river restoration project. The energy dissipation of a block ramp changes with the tailwater level. In this technical note the relative energy dissipation in submerged flow conditions has been investigated. The experiments were conducted at the Hydraulic Laboratory of the University of Pisa, Pisa, Italy on ramps characterized by different block materials, submergence conditions, and ramp slopes. The study shows that the relative energy loss, varying the hydraulic jump location on the ramp, is essentially a function of the scale roughness, the ramp slope, the ratio between the critical water depth, and the ramp height and the ratio between the ramp length and the reduced length in submerged conditions. The differences in energy dissipation for a submerged hydraulic jump in different bed conditions are also investigated.     

Ti-29Nb-13Ta-4.6Zr高速压制行为及其烧结性能的研究

利用自主研发的机械蓄能式高速压机成形Ti-29Nb-13Ta-4.6Zr粉末并进行真空烧结,研究冲击能量对试样的密度及力学性能的影响。结果表明:随着冲击能量的提高,试样生坯密度提高,在冲击能量为1 805 J时,获得的最大生坯密度达到5.63 g/cm~3(相对密度94.1%);径向弹性后效随着冲击能量增加而增加;经真空1 250℃烧结后,烧结坯的密度随着冲击能量的增加而增加,但烧结坯的体积发生了膨胀,最大烧结密度为5.53 g/cm~3(相对密度为92.5%);真空烧结2.0 h后,钛合金的抗拉强度和硬度达到最大值,分别为629.8 MPa和324.5 HV。     

深化模拟市场机制 加大节能技改力度

邯钢是国家“八五”节能先进企业，在5年间钢产量翻了一番，总能耗仅增加50％。文中提出了进一步挖掘节能降耗潜力、创造节能型企业的奋斗目标和实施措施。     

我国节能近况与对策

节能已成为我国可持续发展的重要组成部分,《节能法》的颁布实施使节能受到更广泛的重视。本文介绍了我国1997年及1998年初的节能状况和国家有关政策及措施,分析我国节能工作存在的主要问题;并介绍了我国1998年的节能计划和对策。     

节能是发展钢铁工业的基础工作

我国人均能源资源相对短缺、钢铁产品单位能耗高于国际先进水平３０％左右，节能任务繁重。本文在回顾节能工作、成就和差距的基础上，建议建设节能型工厂、充分利用余能和余热资源、淘汰平炉和化铁炼钢等落后工艺技术、利用现代科学技术加强能源管理等，确保在２０００年吨钢综合能耗达到１．２８６ｔｃｅ。     

Changes in the Grain Boundary Character and Energy Distributions Resulting from a Complexion Transition in Ca-Doped Yttria

The grain boundary character distribution and the relative grain boundary energy of 100?ppm Ca-doped yttria were measured before and after a previously identified grain boundary complexion transition. The grain boundary character distribution of samples exhibiting normal grain growth (before the complexion transition) favored {111} planes, whereas those exhibiting abnormal grain growth (after the complexion transition) favored {001} planes. Additionally, the relative grain boundary-to-surface energy ratios in the sample exhibiting abnormal grain growth were 33?pct lower than in the sample exhibiting normal grain growth. The results also indicate that the complexion transition increased the anisotropy of the grain boundary energy, and this may be responsible for the increase in the anisotropy of the grain boundary character distribution.