GCr15表面TiC/Fe复合层的制备及其与基体结合性能分析

研究以GCr15和TC4为原料,采用热压扩散原位反应在GCr15表面制备TiC/Fe复合层. 利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、自动划痕仪和显微硬度仪测试表征复合层的物相组成、显微组织、复合层的界面结合性能和显微硬度的变化. 结果表明,在1000 ℃和40 MPa条件下保温2 h,4 h和6 h后,TiC/Fe复合层厚度分别为5 μm,7 μm和10 μm,复合层厚度均匀,与基体界面平整,其表面物相组成仅为TiC和α-Fe相,复合层的显微硬度最高达到2453.7 HV0.05,约为轴承钢基体的5倍. 显微划痕与拉伸试验可知1000 ℃和40 MPa条件下保温4 h所得复合层与基体界面结合的临界载荷为58.5 N,界面结合强度大于221 MPa,表明热压扩散原位制备GCr15表面TiC/Fe复合层与基体之间具有优异的结合性能,对基体保护作用良好.     

CoCrFeMnNi/6061Al复合材料制备及微区力学性能研究

通过放电等离子烧结(SPS)制备了CoCrFeMnNi/6061Al复合材料,采用SEM、XRD和纳米压痕等手段对其界面形貌和微区力学性能进行分析。结果表明,基体和增强颗粒间形成了厚度约为20μm的反应界面层,并生成了BCC固溶体相;复合材料微区的弹性模量和硬度变化趋势相同;界面层上的微纳力学性能高于基体和增强颗粒,界面层对复合材料力学性能的提高起重要的作用。     

铝合金/碳钢激光-TIG复合热源熔钎焊工艺与接头显微结构分析

文中提出了一种激光-TIG复合热源熔钎焊新方法,实现了铝合金与碳钢的对接熔钎焊,并研究了焊接工艺对接头特性的影响.采用扫描电镜（SEM）、能谱分析（EDS）和电子材料试验机对接头显微结构与力学性能进行研究.结果表明,接头最大抗拉强度为83.6 MPa,断裂发生在钢/焊缝界面,断裂形式为脆性断裂.钢/焊缝界面不同位置处界面层厚度不同,在3~12 μm之间.界面层由两部分组成,即靠近钢一侧为η-Fe₂Al₅,靠近焊缝一侧为τ₅-Al_7.2Fe₂Si;远离界面层的焊缝区主要由α-Al基体和Al-Si共晶相组成.     

高钒高速钢/35CrMo复合轧辊界面组织和性能研究

采用电磁半连续复合铸造法制成高钒高速钢35CrMo复合轧辊，研究了复合界面组织形貌特征和微区成分分布，测试了结合界面的力学性能。结果表明：界面上有厚度为40μm左右扩散层，层内显微组织为珠光体；邻接扩散层的合金钢侧组织为铁素体和珠光体，高速钢侧为马氏体基体上分布着VC颗粒。高速钢和舍金钢的显微硬度值分别为700HV和250HV，扩散层介于两者之间硬度值为350HV；冲击韧度值可达到100J／cm^2。该方法制备的复合轧辊界面具有良好的组织特征和力学性能，是冶金结合和扩散结合共同作用的结果。高钒高速钢35CrMo复合界面存在明显扩散层，且界面两侧发生成分扩散。结合区两侧显微硬度差别很大，但在界面处无突变。界面冲击韧度随高钒高速钢面积比的增加快速下降。     

压痕对表面感应淬火中碳钢疲劳性能的影响

对S38C中碳钢进行表面感应淬火+低温回火处理,对处理后的试样显微组织、截面硬度分布和抗拉强度进行表征,通过疲劳试验和断口形貌分析评价压痕对先压痕后淬火和先淬火后压痕两类试样疲劳性能的影响。结果表明,试样有效淬硬层厚度为700μm,淬硬层有未转变的铁素体存在,最大硬度480 HV0.2在亚表面200μm处。淬火试样抗拉强度比基体材料高140MPa,断裂伸长率只有基体的一半。当压痕较小时,两类试样的疲劳强度没有差异,当试样压痕较大时,淬火后压痕疲劳断面有微裂纹,造成这类试样疲劳强度迅速下降,表面强化材料表面冲击损伤不能简单的当作一般缺陷处理。     

基于原子力显微镜的薄膜原位压痕力学性能研究

基于原子力显微镜(AFM)和扫描电子显微镜(SEM)建立了一套原位纳米压痕测试系统。该系统可以实现控制带有金刚石(Cube corner)压头的AFM微悬臂梁对样品进行压入实验,并得到载荷-位移曲线,同时可以对压痕过程进行原位SEM实时观察。发展了一种基于AFM微悬臂梁加载和原位SEM压痕图像分析的力学性能测试方法,通过测量压入最大载荷和原位SEM测量压痕残余面积得到塑性薄膜的硬度和弹性模量。利用此方法对磁控溅射硅衬底上纳米晶银薄膜进行了压痕实验,并与Nanoindenter G200型纳米压痕仪实验进行对比研究。结果表明,原位AFM压痕方法具有高的载荷和位移分辨率,可以实现纳牛至微牛级的压痕实验,通过测量压痕面积得到塑性薄膜的硬度值,减小了使用Oliver-pharr方法中软膜硬基底上凸起(Pile-up)效应的影响,计算结果也具有好的测试精度和可靠性。     

生成相性质及其对TiAl合金/42CrMo钢钎焊接头力学性能影响

在钎焊温度1123~1273 K,保温时间120~1500 s参数范围内对TiAl合金与42CrMo钢进行了真空扩散钎焊.用光学显微镜、扫描电镜和能谱分析等方法对界面组织进行了分析,用图像分析软件工具测量了反应层厚度;采用纳米压痕仪和显微硬度仪对TiAl合金/42CrMo钢钎焊接头的两种母材和接头界面反应相进行了硬度测试,对结果进行了对比,为了确定接头的薄弱环节,进行了扫描电镜原位观察下的接头拉伸试验.结果表明,AlCuTi,Ti₃Al,AlCu₂Ti和TiC的硬度较高,而银的固溶体硬度较低;纳米压痕的硬度结果比显微硬度值略高;扫描电镜下的原位拉伸试验结果表明,Al-Cu-Ti系反应层在受外力作用下容易发生脆性断裂,为接头的薄弱环节.     

生成相性质及其对TiAl合金/42CrMo钢钎焊接头力学性能影响

在钎焊温度1 123~1 273 K,保温时间120~1 500 s参数范围内对TiAl合金与42CrMo钢进行了真空扩散钎焊.用光学显微镜、扫描电镜和能谱分析等方法对界面组织进行了分析,用图像分析软件工具测量了反应层厚度;采用纳米压痕仪和显微硬度仪对TiAl合金/42CrMo钢钎焊接头的两种母材和接头界面反应相进行了硬度测试,对结果进行了对比,为了确定接头的薄弱环节,进行了扫描电镜原位观察下的接头拉伸试验.结果表明,AlCuTi,Ti3Al,AlCu2Ti和TiC的硬度较高,而银的固溶体硬度较低;纳米压痕的硬度结果比显微硬度值略高;扫描电镜下的原位拉伸试验结果表明,Al-Cu-Ti系反应层在受外力作用下容易发生脆性断裂,为接头的薄弱环节.     

包覆率对直接水冷铸造法制备包覆铸锭界面组织和性能的影响（英文）

采用数值模拟和实验相结合的方法研究了不同包覆率的AA4045/AA3003铝合金包覆铸锭的制备,并对界面处的温度场和组织性能进行了详细分析。结果表明,采用直接水冷铸造法可得到不同包覆率的铸锭,Si和Mn在界面处发生了互扩散并形成扩散层。随着包覆率的增加,两种合金接触时界面区域由半固态-固态转变为液态-固态,界面处硬度由HV 47增加到HV 55,扩散层厚度由10增加到25μm。界面处硬度高于AA3003合金一侧,低于4045合金一侧,这是由元素扩散引起固溶强化造成。均匀化退火后,在包覆铸锭被反向挤压成复合管材的过程中,界面处保持层状结构不变,包覆率在变形过程中的遗传性得到证实。     

轧制复合板及焊接接头组织与力学性能

为了能够更好的指导复合材料焊接工艺的制定，采用自熔等离子弧焊、埋弧焊和钨极气体保护焊3种焊接方法进行组合焊接。焊后通过金相显微镜、扫描电子显微镜、X射线能谱仪等分析方法，分析了轧制复合板及其接头的微观组织、界面元素分布、显微硬度及拉伸性能。结果表明，基材和覆材（复合材料的耐腐蚀层）界面元素扩散层厚度约10μm，由于增碳层和脱碳层的存在，显微硬度值随之升高和降低，抗拉强度达665 MPa，断口形貌呈韧脆混合断裂特征。焊接后，基材与过渡层焊缝界面扩散层厚度约5μm，基材与覆层焊缝界面扩散层厚度约3μm；第一道覆层焊缝由于受到多道焊缝焊接热的作用，铁素体体积分数含量达65%，平均显微硬度约380 HV0.2；接头抗拉强度与复合板相比降低约11%，断口韧窝大小、深度明显减小，断裂在焊缝处。     

Galvanic Series of Metals and Effect of Alloy Compositions on Corrosion Resistance in Sanya SeawaterEI北大核心CSCD

With the development of ocean engineering, various metallic materials have been applied to the marine environment. It is an urgent requirement to study the galvanic series and alloy composition optimization of metallic materials in the tropical marine environment. In this work, open circuit potentials (OCP) and galvanic series of 36 kinds of metallic materials in Sanya seawater were studied. By considering the response of OCP to tidal changes, the anti-corrosion effects of alloying elements were also ana lyzed. The results show that the OCP of metallic materials in Sanya seawater has a large range. The galvanic series order of metallic materials from high to low in Sanya seawater is: nickel alloy, duplex stainless steel, austenitic stainless steel and pure copper, ferritic stainless steel, martensitic stainless steel, copper alloy, low alloy steel, carbon steel, cast iron, aluminum alloy and aluminum anode. Low-carbon high-alloy content carbon steel and high Cr, Ni contents stainless steel have higher OCP. The potential fluctuations of carbon steel with tidal changes involves two phases: (1) under the dynamics control, the OCP of carbon steel is more negative at high tide; (2) under the diffusion control, the OCP is more positive at high tide. The potential fluctuations of metallic materials reflect the effect of the corrosion product film on the change of ionization balance, and metals with less potential fluctuations have better inhibition on ion diffusion. In Sanya seawater, the carbon steel, which has more alloying content and less carbon content, has less potential fluctuations with the tidal changes and has good oxygen diffusion resistance. The potential fluctuations of austenitic stainless steel with tidal changes are less than that of ferritic stainless steel and martensitic stainless steel. After 2700 h immersion, austenitic stainless steel and martensitic stainless steel, which have a higher content of Mo, have more stable OCP. In other words, the corrosion film gets a better corrosion resistance. The OCP of aluminum anode in Sanya seawater environment increases when the oxygen content is brought up. The OCP of Zn-containing or Ga-containing aluminum anode remains relatively stable. Al bronze and T2 copper have less potential fluctuations with tidal changes, and perform good corrosion resistance in Sanya seawater.     

Ti8LC钛合金与主要结构材料的电偶腐蚀及防护研究

通过测定表面防护处理前后,Ti8LC钛合金、7710铝合金、ZL59铝合金、30CrMnSiA高强钢的电极电位,以及Ti8LC钛合金与其余3种材料组成偶对后的电偶腐蚀电流-时间曲线,研究了表面防护处理前后3种偶对的电偶腐蚀行为,并评估了电偶腐蚀敏感性.研究结果表明:Ti8LC与7710铝合金、ZL59铝合金、30CrMnSiA钢偶接时,会产生严重的电偶腐蚀,必须进行表面防护处理才能使用;采用涂层前处理+有机涂层防护的方法,可有效阻止Ti8LC钛合金与铝合金和高强钢的电偶腐蚀.     

工业材料的微生物腐蚀

综述了碳钢,不锈钢,铝合金,铜合金,镍合金,钛合金,混凝土及其它非金属材料微生物腐蚀研究中的一些新进展。     

镁合金在大气环境中电偶腐蚀行为及规律的研究

在北京大气环境下，研究AM60镁合金和不同金属材料（碳钢、不锈钢、黄铜和铝合金）偶接的电偶腐蚀行为规律。研究表明，镁合金作为阳极发生不同程度的电偶腐蚀，通过1a的北京大气环境下的暴露试验后，AM60镁合金的电偶腐蚀效应由强到弱的顺序为：碳钢、黄铜、不锈钢和铝合金，其中镁合金与LY12铝合金偶接的电偶腐蚀效应最小。通过与其它地区室外暴晒的镁合金电偶腐蚀效应的对比，表明环境因素影响着镁合金的电偶腐蚀效应。同时阴极材料、试验时间、试样尺寸（偶接面积）和试验环境都会对镁合金电偶腐蚀效应产生影响。经1a曝晒的AM60镁合金形成了具有保护性的腐蚀产物层阻碍了腐蚀发展。北京地区高自然降尘量导致金属表面湿润时间加大，从而加速了AM60镁合金的电偶腐蚀。采用XRD方法分析表面的腐蚀产物，用金相显微镜和扫描电镜（SEM）观察试样腐蚀后的表面形貌特征和腐蚀产物的结构，并用与之相连的能谱仪分析腐蚀产物中的元素组成。     

0Cr13Ni8Mo2Al钢与铝合金和钛台金接触腐蚀与防护研究

通过测定0Cr13Ni8Mo2Al钢与铝合金（LY12）和钛合金（TC4）组成的电偶对的电偶电流的方法,研究了0Cr13Ni8Mo2Al钢在使用中与铝合金和钛合金接触时发生电偶腐蚀的敏感性。研究结果表明:0Cr13Ni8Mo2Al钢与铝合金接触时会产生严重的电偶腐蚀,必须进行防护处理方可使用;与钛合金接触时产生的电偶腐蚀很轻微,可以不进行防护。0Cr13Ni8Mo2Al钢表面进行镀镉钛防护后,与铝合金接触时的电偶电流密度大为减小,相差近10倍;采用环氧锌黄底漆、XM-33-4双组分密封胶防护可以有效地防止0Cr13Ni8Mo2Al钢与铝合金和钛合金接触产生的电偶腐蚀。     

不锈钢／铝合金／不锈钢多层复合板的成形性能

通过拉伸实验测试了不锈钢／铝合金／不锈钢三层、五层复合板的成形性能影响参数：厚度异性系数r、应变强化指数n和屈强比σ0．2／σb，结果表明轧制复合变形量、扩散退火温度对不锈钢／铝合金／不锈钢多层复合材料的成形性能参数有较明显的影响。     

Microbial Activities’ Influence on Three Kinds of Metal Material Corrosion Behaviors

The corrosion behaviors of copper, 6063 aluminum alloy, and Q235 steel were investigated by open-circuit potential (OCP), anodic polarization curve analysis, and electrochemical impedance spectroscopy (EIS). Scanning electron microscopy revealed that a small number of translucent rod-shaped bacterial colonies on the copper surface of copper, whereas plenty of rod-shaped microbes colony were detected on the surface of 6063 aluminum material. Moreover, rod-shaped bacteria and mold colonies attached to the surface of Q235 steel. The decrease in the OCP of copper, 6063 aluminum alloy, and Q235 steel led to higher corrosion tendency. EIS analysis showed that bacteria can reduce the value of AC impedance of copper, the polarization resistance, and the surface resistance, thereby accelerating corrosion. Moreover, the polarization resistance of aluminum alloy in bacterial seawater is lower than that in non-bacterial seawater, indicating the existence of bacteria accelerated the corrosion of 6063 aluminum alloy. The adherence of microbes on Q235 steel surface accelerated the dissolution of the surface layer, and then the passive film is replaced by incompact biofilm layer. Q235 steel corrodes faster under the influence of bacteria because the polarization resistance in bacterial seawater is much lower than that in non-bacterial seawater.     

铝合金船体与不锈钢阀件的腐蚀及电化学特性

在不锈钢基体上分别镀上几种镀层,各自与船用铝合金配对测腐蚀速率，并测定了镀层在海盐溶液（3.5%）中的电极电位与极化曲线.结果表明，镀Zn-Ni的18-8钢自身腐蚀不大，还可使船体材料的腐蚀速率最小.      

On the growth of intermetallic phases by heat treatment of friction stir welded aluminum steel joints

Multi-material components made from aluminum and steel sheet metal are an innovative approach for weight reduction in automotive applications. However, lightweight components made from aluminum and steel require suitable joining technologies. A promising solid-state welding technology for producing dissimilar steel aluminum joints is Friction Stir Welding, which minimizes the formation of Fe-Al intermetallic phases due to process temperatures lower than the melting temperatures of the base material. The results obtained show a comparison of steel aluminum joints made by FSW using DC04 mild steel with the strain hardened aluminum alloy AA5754-H22 on the one hand and the precipitation hardened aluminum alloy AA6082-T6 on the other hand. The difference between achieved maximum tensile strengths of the joints in relation to those from both base materials is investigated. Due to the stirring and heat input of the welding process, the temper condition of the precipitation hardened aluminum alloy is changed. To improve the mechanical properties of the welded joints, post weld heat treatments are performed. The post weld heat treatments of the produced multi-material specimens from AA6082-T6 aluminum alloy and mild steel at various heat treatment conditions show substantial growth of intermetallic phase layer, which is characterized in detail within the present work. Tensile tests show a degradation of the mechanical properties resulting in a decreased tensile strength and insufficient connection of both materials. Investigations using a scanning electron microscope (SEM) show a distinct increase of the thickness of intermetallic phases in the transition between aluminum and steel.     

Brazing zirconium alloys with an amorphous rapidly quenched strip brazing alloy

Application of aluminum alloy, which is a typical lightweight material, has been expected to achieve energy saving and prevention of pollution in many kinds of transportation vehicles. While the structure made of whole aluminum alloy, however, is lightweight, it still has problems, such as low mechanical strength and high cost. Hence, a hybrid or joining structure made of aluminum alloy and steel seems to be reasonable because of its light weight and higher strength.

To make a hybrid structure for transportation vehicles, we examined welding by friction stirring between aluminum alloy and low-carbon steel, which could be welded without melted weld materials. As a result, welding between aluminum alloy and low-carbon steel that had a thin intermetallic compound at the weld interface was obtained.

In recent automobile manufacturing, zinc-coated steel has been used for structural parts in general. On welding between zinc-coated steel and other materials such as aluminum alloy, existence of a Zn layer between aluminum and steel has to be taken into account to get a high-quality joint between the materials.

In this study, spot joining between aluminum alloy and several kinds of zinc-coated steels by friction stirring was carried out, and the effect of the coated layer both on the weld strength and weld interface microstructure was investigated. As a result, the joint between aluminum alloy and zinc-coated steel was stronger than that between aluminum alloy and non-coated steel, when the coated layer was removed at the weld interface by plastic flow of aluminum alloy.