两次冷轧法轧制的无取向硅钢{001}〈210〉织构的发展

在元取向硅钢中，{001}〈210〉织构具有良好的磁性，而采用两次冷轧法（中间退火温度为640℃）能够坩强这种织构。利用电子背散射图形（EBSP），测量退火过程中亚擞织构的变化来研究两次冷轧法生产的无取向电工钢{001}〈210〉奴构的形成机理。中间退火钢板的再结晶份数为60％，主要由〈111〉／／ND小等轴再结晶晶粒和〈110〉／／RD伸长变形晶粒组成．在最终退火期间，再结晶晶粒〈111〉／／ND方向的长大被抑制。晶粒在{001}晶面〈210〉晶向上的长大使〈111〉／／ND方向的再结晶晶粒被消耗。这是由于再结晶晶粒中第二次冷轧在〈111〉／／ND方向引入的应变所造成的。所以，最终退火钢板的结构主要为{001}〈210〉织构。     

保温时间对锰氧化物刻蚀金刚石单晶的影响

研究了在不同保温时间下MnO₂对金刚石单晶的表面刻蚀, 通过扫描电子显微镜和拉曼光谱对刻蚀后金刚石单晶不同晶面的表面形貌和刻蚀机理的进行了表征与分析, 并对腐蚀过程中金刚石表现出来的各向异性进行了探讨。结果表明: 当金刚石和MnO₂质量比为1:5时, 金刚石单晶的刻蚀程度随着保温时间的延长而增大; 在相同保温时间下, {111}晶面比{100}晶面刻蚀严重; 金刚石表面腐蚀后的形貌与对应晶面的碳原子排列有关, {100}面倾向于形成四边形的刻蚀坑, 而{111}面则会形成轮廓为三角形的腐蚀坑, 且金刚石单颗粒的抗压强度随刻蚀时间的延长而下降; 刻蚀机理为MnO₂与金刚石表面C原子发生反应, 导致金刚石表面发生刻蚀。     

微碳深冲钢板非{111}织构的形成过程

结合实际生产,采用金相分析、织构测量和透射电镜等方法,研究了微碳深冲钢板中出现的非{111}织构在钢板再结晶时的形成过程,并分析了非{111}织构与冷轧压下率和析出物的关系。研究结果表明：非{111}织构在冷轧变形后即已形成,冷轧压下率较小时,非{111}织构组分相对{111}织构较强;冷轧组织中存在的非{111}取向晶粒在退火过程中会优先成核和优先生长;非{111}织构的形成对AlN的析出不敏感。     

晶体行为对SUS304钢表面溅射蚀刻圆锥状碳化物生成的影响

研究用射频磁控溅射设备对SUS304钢表面进行600 W×14.4 ks或600 W×28.8ks的Ar+溅射蚀刻处理,并用SEM、SIM和EBSP对表面形貌进行微观表征。结果表明:600W溅射蚀刻功率下,圆锥状碳化物不仅沿晶界生成,而且在晶粒表面内大面积生成。其大小和分布密度在{111}面最大,依次按{110}面和{100}面的顺序递减,并于位错等晶体缺陷处优先成核生长。但是,随着时间的延长,晶体取向对碳化物的生长没有直接的影响,微细凸起物形成的碳化物层覆盖试验片,并在局部生成尖而细的凸起物。     

第一性原理计算Si和Ga掺杂对BCC-Fe广义层错能的影响

采用第一性原理计算了BCC-Fe以及BCC-Fe分别掺杂硅(Si)、镓(Ga)后{112}<111>滑移系的广义层错能。结果表明：Si和Ga均会降低BCC-Fe的广义层错能，对广义层错能曲线峰值的降低幅度分别为8.48%和10.27%;不同元素掺杂也会影响层错发生的位置，Si掺杂的BCC-Fe趋向于在Si原子所在的{112}面发生<111>方向的层错，而Ga掺杂的BCC-Fe更趋向于在与Ga原子近邻的{112}面发生<111>方向的层错。此外，BCC-Fe上下层沿着{112}<111>滑移系错动2/3b_p(b_p=1/2<111>)时，会形成薄层孪晶结构，使2/3b_p处的广义层错能显著降低。与错动1b_p后形成的完美晶体相比，薄层孪晶为亚稳定状态，可通过相邻的{112}平行晶面逐层错动2/3b_p,从而生成多层孪晶来进一步降低层错能，一定程度上解释了Fe-Si、Fe-Ga合金中发现大量∑3孪晶界的现象。     

La2O3刻蚀对金刚石单晶性能的影响

以氮气为保护气氛,在820～980℃下用La₂O₃刻蚀人造金刚石单晶表面,研究稀土氧化物La₂O₃刻蚀对人造金刚石单晶性能的影响。利用扫描电子显微镜观测刻蚀后金刚石单晶不同晶面的表面形貌,通过人造金刚石单晶表面粗糙度、单颗粒抗压强度、抗冲击韧性和铜基结合剂金刚石节块抗弯强度来表征刻蚀前后金刚石单晶性能的变化。结果表明：La₂O₃对金刚石{100}面和{111}面的刻蚀是各向异性的;当刻蚀温度从820℃升高到980℃时,{100}面表面粗糙度从0.40μm增加至2.28μm,{111}面表面粗糙度从0.70μm增加到3.32μm,金刚石单颗粒的抗压强度由未刻蚀金刚石的576 N降低到最小530 N,冲击韧性由92.94%下降到89.21%。当金刚石体积分数为5%时,刻蚀后金刚石节块的抗弯强度增幅达到17.9%。     

铌中氢的行为

本文用室温电解法在多晶铌中渗氢,研究氢在铌中的行为。金相、扫描电镜和离子探针分析表明,氢含量不高时氢化物首先在晶界析出,然后向惯习面扩展。氢化物形态与氢含量有关。低的氢含量生成片状氢化物;高的氢含量形成氢化物畴结构。有人用马氏体相变的唯象晶体学理论推断氢化物可能的析出面,指出氢化物的惯习面随氢含量而变。我们用X射线劳埃背射法测出纯铌中氢化物析出惯习面为{130}c,{111}c,用X射线粉末法确定在室温电解渗氢6小时(电流密度0.2安/厘米~2)所形成氢化物的结构与NbH0.89相同。     

一种单晶高温合金不同温度的高周疲劳性能

研究了一种单晶高温合金700 ℃和800 ℃的高周疲劳性能，采用扫描电镜和透射电镜分析了断口和断裂机制.结果表明，随着温度升高，合金的疲劳强度系数降低，Basquin系数增加，高周疲劳极限降低.合金700 ℃与800 ℃具有相同的高周疲劳断口，都有几个{111}面平面组成，为类解理断裂机制.疲劳断口由裂纹源区、扩展区和瞬断区3部分组成.裂纹起源于试样的表面或亚表面，并沿{111}面扩展.扩展区可见河流状花样、滑移带、疲劳弧线和疲劳条带特征.瞬断区可见解理台阶和撕裂棱.断裂后γ′相仍保持立方形状，位错不均匀分布在γ基体通道中.      

不同织构组分对IF钢板R(θ)值起伏的影响

检测了宝钢两组IF钢板与轧向夹角分别为0°,15°,30°,45°,60°,75°,90°的R值以及板材的织构。计算了板材的{001}<110>、{112}<110>、{110}<001>、{111}<110>和{111}<112>织构组分的体积量,利用Sachs模型分析了{112}<110>和{110}<001>织构对轧板上不同方向的R值的影响。结果表明,IF钢板板面不同方向上存在R值的显著起伏。计算与实测结果表明,{112}<110>和{110}<001>织构是造成板材R(θ)值起伏的重要因素。在增大{111}面织构并减小{100}面织构的同时,合理控制{112}<110>和{110}<001>织构组分有可能使深冲压钢板获得高R值的同时明显降低R值的起伏。     

冷轧压下率对连续退火Ti-IF钢组织和织构的影响

以工业生产的Ti-IF钢热轧板为研究材料,结合连续热镀锌线的工艺特点,采用实验室冷轧、盐浴退火方法和金相、X射线织构测试等分析手段,研究了冷轧压下率对组织和织构的影响规律。试验结果表明,随着冷轧压下率从60%提高到90%,冷轧态α取向线上的取向密度不断增强,而且主要形成了{223}110和{114}110织构,γ线上的{111}110和{111}112织构亦有所增强;退火后铁素体晶粒尺寸从9.0级细化到10.5级;试验钢退火后仍具有较强的{223}110和{114}110织构,且随着冷轧压下率的提高,{111}织构有增强的趋势。要获得强的{111}织构,冷轧压下率需在80%以上。     

Evolution of Through-Thickness Texture in Ultra Purified 17%Cr Ferritic Stainless Steels

 Texture inhomogeneity usually takes place in ferritic stainless steels due to the lack of phase transformation and recrystallization during hot strip rolling, which can deteriorate the formability of final sheets. In order to work out the way of weakening texture inhomogeneity, conventional hot rolling and warm rolling processes have been carried out with an ultra purified ferritic stainless steel. The results showed that the evolution of through-thickness texture is closely dependent on rolling process, especially for the texture in the center layer. For both conventional and warm rolling processes, shear texture components were formed in the surface layers after hot rolling and annealing; sharp α-fiber and weak γ-fiber with the major component at {111}<110> were developed in both cold rolled sheet surfaces, leading to the formation of inhomogeneous γ-fiber dominated by {111}<112> after recrystallization annealing. In the center layer of conventional rolled and annealed bands, strong α-fiber and weak γ-fiber textures were formed; the cold rolled textures were comprised of sharp α-fiber and weak γ-fiber with the major component at {111}<110>, and inhomogeneous γ-fiber dominated by {111}<112> was formed after recrystallization annealing. By contrast, in the centre layer of warm rolled bands, the texture was comprised of weak α-fiber and sharp γ-fiber, and γ-fiber became the only component after annealing. The cold rolled texture displayed a sharp γ-fiber with the major component at {111}<112> and the intensity of γ-fiber close to that of α-fiber, resulting in the formation of a nearly homogeneous γ-fiber recrystallization texture in the center layer of the final sheet.     

Fracture of single crystals of the nickel-base superalloy PWA 1480E in hydrogen at 22 °C

The hydrogen-induced fracture behavior of notched single crystals of the PWA 1480E nickel-based superalloy was studied. Notched single crystals with seven different crystal orientations near [100], [110], [111], [013], [112], [123], and [223] were tensile tested at 22 °C in an hydrogen atmosphere at 34 MPa. The notch tensile strength degradation in hydrogen was orientation dependent. The specimen with the [100] orientation had the greatest strength degradation, while the crystal with the [111] orientation had the least. A stereoscopic technique combined with the use of planar γ′ morphologies was applied to identify cleavage plane orientations. All specimens failed predominately by {100}-type cleavage within about 0.5 mm of the notch and {111}-type cleavage toward the center of the crystal. Cleavage on {111}-type planes in the center of the crystals was not related to testing in hydrogen. Microcracking along the {100} γ/γ′ interfaces was observed in the area near the fractured surface. Both scanning electron microscopy (SEM) and transmission electron microscopy (TEM) studies indicated that {100}-type cleavage within the notch region controlled the hydrogen-induced cleavage fracture in notched single crystals. Formerly graduate Student, Auburn University     

Hydrogen effects in [001] oriented nickel-base superalloy single crystals

The entry and subsequent interaction of hydrogen on the mechanical properties of the single crystal nickel-base super alloy CMSX-2 has been studied. Significant amounts of hydrogen were introduced by high temperature hydrogen charging in molten salts which led to an increased lattice parameter and microhardness and to a degradation in tensile elongation to failure whose extent scales with the depth of the hydrogenated zone. In this region a fracture mode change from a {111} to a {100} type also occurred. The values of the binding energy of hydrogen to solidification voids and the effective hydrogen pressure in the voids were estimate.     

Faceted growth of silicon crystals in Al-Si alloys

Primary silicon crystals in hypereutectic aluminum-silicon alloy castings frozen at moderate rates have been studied metallographically. Etched growth traces parallel to external facets were used to demonstrate that the majority of the crystals, though of widely varying external shape, grow in basically octahedral form, enclosed in {111} facets. Equations are developed that predict the limits within which true octahedral or spinel-type growth can occur. The equations are tested by measurements of growth trace spacings. Outside the predicted limits, there can be accelerated corner growth, which may result in hollow hopper crystals or even a dendritic form. Alternatively, a corner may be truncated by formation of a facet other than {111}.     

The mechanism of silicon modification in aluminum-silicon alloys: Impurity induced twinning

Modification of silicon by sodium in aluminum silicon eutectic alloy has been examined in detail by optical, SEM, and TEM methods. The aluminum phase is not significantly affected but the silicon becomes very heavily twinned. Modification by quenching does not involve an increase in twin density. Consideration of the atomic positions which attend the formation of growth twins on {111} planes suggests that adsorbed impurity atoms of suitable size, on the solid-liquid interface, could be responsible for changing the {111} stacking sequence, so promoting ‘impurity induced twinning’; the optimum hard sphere radius ratio would be ≈ 1.65. It is proposed that this condition could be the first and principal requirement for a modifying agent to be effective in this system. It is shown further, that other reputed modifiers do also induce a higher twin density. Variations in the efficiency of individual elements to promote such an effect are discussed in terms of other relevant factors which include melting points and vapor pressures, the free energies of formation of compounds — notably of oxides, and the forms of alloy phase diagrams. Formerly Visiting Scholar at Michigan Technological University     

Vanadium Defects Formation Mechanism in Undoped GaN Grown on Silicon

V defects in GaN layer grown on Si (111) using metalorganic chemical vapor deposition (MOCVD) were investigated by atomic force microscopy (AFM), plan-view transmission electron microscopy (TEM) and energy-dispersive X-ray spectrometer (EDS). Dislocations are the origination of V defects. Stress field around dislocations induce the concentration of C atoms, furthermore, slow growth rate on those {10-11} planes are suggested as being responsible for the initiation of V defects. The formation mechanism of V defects was discussed.     

CSP制无取向硅钢热轧、常化、冷轧织构的演变

运用EBSD和X射线衍射技术,研究了模拟CSP流程生产无取向硅钢在热轧-常化-冷轧过程中织构的演变。热轧板沿板厚方向应力场和温度场的差异导致由表至中织构锋锐度增高,织构类型存在明显变化,表层主织构为B类纤维织构,次表层为A类纤维织构,中心层为旋转立方织构{001}<110>。常化过程削弱了这种差异性,但中心层仍保留了一定强度的立方织构{001}<100>。冷轧板表层及中心层的主织构均为{112}<110>、{111}<112>,表层织构锋锐度较中心层的强。分析表明热轧、常化、冷轧织构的演变与基体初始织构、组织密切相关。表层、次表层热轧板织构经常化演化成散漫、分布较均匀的织构,中心层主要织构由{001}<-1-10>绕RD逆时针旋转45°演化至{001}<0-10>。冷轧后织构演变为以{223}<110>为主的B类织构和以{111}<112>为主的A类织构。     

卢瑟福背散射谱和红外干涉反射谱研究冷注入锗离子

主要研究锗离子在77 K温度下的冷注入对单晶硅片表面的预非晶化效果, 并与室温注入情形予以对比. 卢瑟福背散射谱(RBS)和红外干涉反射谱被用于对非晶层的研究. 实验表明, 冷注入要比室温注入的退沟道效应更为显著, 反射率降低更为明显, 意味着引入的损伤更为严重, 更容易使硅单晶非晶化. 而且, 冷注入产生的最大损伤峰比室温注入的位于更深的位置, 相应的非晶层/硅单晶衬底界面有更深的推入. 结果还表明, 同样的注入温度下, 剂量越大, 损伤越严重.     

合金元素对硅钢性能的影响

介绍和分析了Ｃ，Ｓｉ，Ｐ，Ａｌ，Ｃｕ，Ｓｎ和Ｓｂ等合金元素对硅钢性能的影响和合金元素对硅钢性能影响的机理。Ｐ，Ａｌ，Ｃｕ为钢中的主要杂质元素，但适量Ｐ可提高硅钢的防锈能力。锡和锑是表面活性元素，它们可使硅钢最终退火织构中｛１１１｝面组分减少，｛１００｝和｛１１０｝面组分增加，从而降低硅钢铁损，提高其磁感应强度。     

某些元素对硅钢性能的影响

介绍了硅钢中某些元素对其性能的影响，并扼要分析了某些元素对硅钢性能影响的机制。其中碳是引起硅钢发生磁时效的重要元素之一，随着硅钢中碳含量的增加，其铁损增加；而硅含量增加能显著降低硅钢铁损。磷、名、铜是主要杂质元素，但适量的磷可提高硅钢的防锈能力。锡和锑均是表面活性元素，它们可使硅钢最终退火织构中｛１１１｝面组分减少，｛１００｝和｛１１０｝面组分增加，从而降低硅钢铁损，提高其磁感应强度。