铝/钢爆炸复合界面的显微分析

通过金相显微镜与电子探针对铝/钢复合板的界面进行了显微分析.结果表明,铝、钢爆炸复合过程中不易形成波状界面,复合界面呈平直状,界面处金属发生了冶金反应;爆炸焊接过程中,铝/钢复合界面处的基体金属发生了熔化,界面处的晶粒发生了严重的塑性变形,并且在铝/钢直接结合的界面两侧存在着距离约为5μm的扩散.分析认为爆炸焊接的工艺特点及铝、钢的物理性质决定了铝/钢界面的显微特点.并据此探讨了影响铝/钢复合强度的因素.     

固溶处理冷却方式对Cu/Al复合板界面微观组织的影响

利用光学显微镜、扫描电镜、X射线衍射等手段研究了冷却方式(水冷、空冷和炉冷)对Cu/Al复合板界面微观组织的影响,利用显微硬度仪测试了冷却方式对铸轧Cu/Al复合板力学性能的影响。实验结果表明:铸轧复合板界面形成Al_2Cu、AlCu、Cu_9Al_4、AlCu_3四种金属间化合物,经500℃×2 h固溶处理后,界面扩散层厚度增加,形成Al_2Cu、AlCu、Al_2Cu_3、Cu_9Al_4、AlCu_3五种金属间化合物。水冷和空冷界面扩散层产生孔洞,炉冷孔洞基本消失,解释了孔洞形成原因及变化过程,孔洞等缺陷会削弱界面层的结合强度。铸轧复合板界面扩散层厚度小、硬度低;经固溶处理后,界面扩散层厚度和硬度均增加,并随冷却速度的减小,厚度和硬度进一步增加。剥离过程中,铸轧复合板靠近Al基体断裂,而经固溶处理后的复合板断裂在界面扩散层。随冷却速度的下降,裂纹扩展能力减弱,过厚的金属间化合物不利于复合板的结合。     

Pb1-Q245R爆炸焊接复合板结合界面研究

采用电阻测量装置、金相显微镜、透射电镜对爆炸焊接铅-钢复合板结合界面进行了研究.结果表明,铅-钢复合板结合界面导电性能优越;界面结合形态呈准正弦波形,无漩涡区;结合界面两侧的铅元素和铁元素相互扩散,钢侧铅含量降低较快,铅侧铁含量降低较慢,扩散的深度在微米数量级;结合界面组织由铁微晶与铅微晶混合组织组成.     

铁铝焊接界面组织与性能的研究

为了研究热处理对铁铝焊接界面组织和性能的影响,本文采用电容储能焊得到铁铝焊接接头,并对部分焊接接头进行热处理。利用显微镜、X射线能谱仪和显微维氏硬度仪对未热处理和热处理的焊接接头界面处的微观组织、化学成分和性能进行对比和分析。结果表明:热处理后焊接接头界面处有Fe-Al金属间化合物生成;热处理后的焊接接头融合区的铝含量比未热处理的低;焊接接头界面处由于铁铝原子的互扩散,硬度较铁、铝基体有所提高;热处理的焊接接头界面处的硬度高于未热处理的界面处硬度。热处理促使金属间化合物的生成,有利于改善焊接接头性能。     

界面微合金化对钢/铝复合板性能影响的研究

研究了微合金化和温度对钢/铝复合板结合强度的影响.通过光学显微镜和X射线衍射仪观察、检测了结合界面的微观结构,并进行剥离强度的测试.结果表明钢铝复合界面扩散反应生成的化合物为Fe2Al5,温度对复合板的界面结合强度影响极大,界面微合金化能显著提高钢/铝复合板界面性能.     

铝合金-钢爆炸焊接装药量与界面性能的关系(英文)

通过设计不同的爆炸焊接工艺参数爆炸复合了铝合金-钢爆炸复合板,并对复合板的界面性能进行了显微分析和力学性能测试,探讨了爆炸焊接装药量对复合板界面性能的影响。结果表明:在铝合金-钢复合板的的结合界面产生了一层金属间化合物并且在化合物中产生了许多微裂纹。随着装药量的增加,界面化合物的厚度略有增加,其上微裂纹的的数量也有所增加。复合界面的剪切强度随着装药量的增加而有所降低。界面化合物对复合板强度产生不利影响,铝合金-钢爆炸焊接时应尽量采用小药量。     

铝合金与镀锌钢脉冲旁路耦合电弧GMAW熔钎焊搭接工艺及接头性能的研究

采用脉冲旁路耦合电弧GMAW熔钎焊方法,以ER4043焊丝为填充材料,实现了铝合金与镀锌钢异种金属的熔钎焊接,得到外观成形良好、变形小的搭接接头。通过SEM、EPMA、EDS、显微硬度计和拉伸实验机对搭接接头的微观组织及力学性能进行了研究。结果表明:在搭接接头界面中心区的铝侧形成针状或锯齿状的FeAl3金属间化合物,而在钢侧形成平齐的Fe2Al5和Fe0.7Al3Si0.3金属间化合物。显微硬度测试分析进一步证明了铝合金与镀锌钢界面中心区由硬度高的金属间化合物组成。搭接接头的平均拉剪强度达到144.85MPa,最高拉剪强度达到186.73MPa,达到了铝合金母材强度的88.5%,且断裂方式为韧性断裂。     

金属镀层对铝/钢激光熔钎焊接头组织与性能的影响

针对在铝/钢焊接过程中,钢的表面金属镀层对铝/钢激光熔钎焊接头性能有着重要影响的问题,研究铝合金在不同金属镀层的低碳钢表面的铺展效果,通过SEM对不同金属镀层下熔钎焊接头界面微观组织形态、金属间化合物厚度、种类等进行分析,并进一步研究不同金属镀层下铝/钢接头的力学性能及断口形貌。结果表明:钢表面的金属镀层对铝/钢激光熔钎焊过程中5A06铝合金在钢上的铺展与浸润有着较大的影响,其中5A06铝合金在镀铝钢上的铺展效果最佳,且铝合金与镀铝锌钢熔钎焊的接头抗拉性能最好,达到母材铝合金的70%。铝/钢界面金属间化合物主要由铝铁金属间化合物组成,其中在镀铝钢、镀铝锌钢、镀锌钢中主要存在Fe2Al5,FeAl3,FeAl等金属间化合物,在镀镍钢界面中还存在Fe4Al13等金属间化合物。     

T6热处理对A356/6082铝合金复合板界面组织及力学性能的影响!

采用液-固轧制复合技术制备A356/6082层状复合板,并对其进行T6热处理。通过光学显微镜(OM)、扫描电镜(SEM)、剪切试验、显微硬度测试等表征手段对比分析了T6热处理前后复合板显微组织变化、界面元素扩散规律以及剪切强度和硬度等力学性能特征。结果表明:T6热处理后,层片状共晶硅形态发生球化,界面附近的共晶硅团聚现象消失且组织更为均匀;界面区Mg元素明显扩散,结合线消失;复合板剪切强度从91. 6 MPa提高到139. 2 MPa,界面区域和基体的显微硬度均得到明显改善,A356侧的平均硬度值达到1102. 5 MPa左右,6082侧的平均硬度值达到851. 6 MPa左右,且沿A356至6082垂直界面方向其显微硬度值逐渐下降。     

T2纯铜/2024铝合金爆炸焊接接头界面结构及性能

为研究铜铝异种金属爆炸焊接头界面形成机理,采用爆炸焊对T2纯铜和2024铝合金进行了焊接.通过光学显微镜、扫描电镜、X射线衍射、万能材料试验机和纳米压痕仪,对T2/2024复合板结合界面的显微组织、成分分布和力学性能进行了测试分析.结果表明:T2/2024合金爆炸复合板结合界面呈波状结合,结合界面主要由平直界面、波状界面和局部熔化层界面构成;靠近结合界面处,基体金属发生塑性变形,晶粒细化;反应层主要成分为AlCu和Al_2Cu的混合物.复合板拉剪试验表明,T2/2024合金爆炸复合板平均结合强度为67 MPa,纳米压痕测试反应层平均硬度可达8 GPa.     

In-situ high temperature X-ray diffraction study of Fe/Al2O3 interface reactions

In-situ experiments on the Fe/Al2O3 interface reaction were carried out with a high temperature X-ray diffractometer capable of measuring the X-ray diffraction pattern in 1–4s, using an imaging plate. The kinetic formation processes of the interface reaction layer were measured in short-period exposure experiments using the apparatus. The time-temperature phase diagram of Fe/Al2O3 in air was determined. Fe/Al2O4 was formed at the FeAl2O3 interface between 1595 K and 1675 K in air. The formation of FeAl2O4 obeyed the parabolic rate law. The value of the activation energy suggests that the diffusion of Al into FeAl2O4 controls the rate of formation. The results of thermal expansion coefficient measurements suggest that when a sample is cooled to room temperature, compressive strain caused by FeAl2O4 occurs on Al2O3.     

Atomistic modeling of plastic deformation in B2-FeAl/Al nanolayered composites

In this work, the deformation response of the B2-FeAl/Al intermetallic composites, as a model material system for nanolayered composites comprised of intermetallic interfaces, has been explored. We use atomistic simulations to study the deformation mechanisms and the interface misfit dislocation structure of B2-FeAl/Al nanolayered composites. It is shown that two sets of dislocations are contained in the interface misfit dislocation network and are correlated with the initial dislocation nucleation from the interfaces. The effects of layer thickness on the uniaxial deformation response of the B2-FeAl/Al multilayers are investigated. We observed that under compressive loading the smaller proportion of the FeAl layers leads to the lower overall flow stress. Under tensile loading, the void formation mechanism is investigated, suggesting the interface structure and the dislocation activities in the FeAl layers playing a significant role to trigger the strain localization which leads to void nucleation commencing at the interface. It is also found that the deformation behavior in the “weak” Fe/Cu interface behaves substantially different than that of the “strong” FeAl/Al interface. The atomistic modeling study of the nanolayered composites here underpinned the mechanical response of “strong” intermetallic interface material systems. There is no void nucleation during the entire plastic deformations in the Fe/Cu simulations, which is attributed to much higher dislocation density, more slip systems activated, and relative uniformly distributed dislocation traces in the Fe phase of the Fe/Cu multilayers.

     

Al-Fe液/固复合界面扩散溶解层研究

采用镶嵌式扩散偶技术制备了Al-Fe扩散偶,在Al熔点以上Fe熔点以下进行扩散热处理,研究了Al-Fe液/固界面扩散溶解层的组织结构演变、形成机理及生长规律。实验结果表明,Al-Fe扩散偶扩散热处理后的组织结构为Al+FeAl3/FeAl3/Fe2Al5/Fe;Fe2Al5层是保温过程中第一个出现的也是唯一出现的连续单相层,FeAl3层则是在冷却过程中形成;Al基中存在针状的和条状的FeAl3析出相,从界面附近到远离界面,析出相的密集程度和尺寸都逐渐小;在相同的保温时间下,热处理温度与扩散溶解层厚度之间存在指数关系;在相同的热处理温度下,保温时间与扩散溶解层厚度偏离抛物线关系。     

硬质相对冷喷涂FeAl金属间化合物涂层性能的影响

FeAl金属间化合物具有优良的物理性能和力学性能,但其室温塑性和断裂韧性低,限制了其工程应用.利用机械合金化制备了Fe(Al)固溶体合金粉末及Al2O3,WC硬质相增强的复合合金粉末,通过冷喷涂沉积涂层并结合后热处理原位反应制备了FeAl金属间化合物涂层及其复合涂层.利用扫描电镜(SEM)、X射线衍射仪(XRD)及显微硬度仪等研究了硬质相对球磨粉末组织结构、冷喷涂FeAl金属间化合物涂层组织结构及性能的影响.结果表明.硬质相可显著加速球磨粉末内部层状结构的细化程度,喷涂态涂层具有不同于传统热喷涂涂层的层状组织结构,热处理可实现喷涂态涂层中Fe(Al)固溶体向FeAl金属间化合物的原位转变,致使层状结构消失,获得无粒子界面的FeAl金属间化合物涂层,弥散分布的硬质相可显著提高冷喷涂FeAl金属间化合物涂层的强化稳定性.     

Structural evolution and grain growth kinetics of the mechanically alloyed Fe50Al50 during heat treatment

Nanocrystalline FeAl powder is synthesized by subsequent heat treating the Fe50Al50 (at.%) alloy prepared by mechanical alloying. During annealing the milled FeAl powder, the grain growth of B2-FeAl occurs with the order transformation from Fe(Al) to B2-FeAl. The activation energy for the nanocrystalline FeAl growth is calculated to be 534.9 kJ/mol, according to the kinetics theory of nanocrystalline growth. The grain growth of FeAl is significantly inhibited especially at elevated temperature.     

Fe－Al系金属间化合物本征脆性的电子理论

利用电子理论计算了Ｆｅ＿３Ａｌ和ＦｅＡｌ金属间化合物的价电子结构和键能，分析了电子分布和晶体键络特性与其室温脆性之间的关系．提出了韧化Ｆｅ—Ａｌ系金属间化合物的可能途径．     

Solid-state reactions underlying mechanochemical synthesis in the Fe-Al system

The sequence of solid-state transformations in the mechanochemical synthesis of Fe-Al intermetallics according to the reactions Fe + Al = FeAl, FeAl + 2Fe = Fe₃Al, and 2FeAl + 3Al = Fe₂Al₅ in powder mixtures has been studied by X-ray diffraction, differential scanning calorimetry, and Mössbauer spectroscopy. The results indicate that the process involves the formation of atomic configurations that may become nuclei of stable or metastable intermediate phases. Prolonged milling leads to homogenization of the synthesis product and the formation of a solid solution or an intermetallic phase with a low degree of long-range order. Complete ordering of the intermetallic phase can as a rule be achieved by heating.     

Effect of heat treatment on the microstructure and property of cold-sprayed nanostructured FeAl/Al2O3 intermetallic composite coating

It is difficult to deposit dense intermetallic compound coatings by cold spraying directly using compound feedstock powders due to their intrinsic low temperature brittleness. A method to prepare intermetallic compound coatings in-situ employing cold spraying was developed using a metastable alloy powder assisted with post heat treatment. In this study, a nanostructured Fe(Al)/Al₂O₃ composite alloy coating was prepared by cold spraying of ball-milled powder. The cold-sprayed Fe(Al)/Al₂O₃ composite alloy coating was evolved in-situ to FeAl/Al₂O₃ intermetallic composite coating through a post heat treatment. The effect of heat treatment on the phase formation, microstructure and microhardness of cold-sprayed Fe(Al)/Al₂O₃ composite coating was investigated. The results showed that annealing at a temperature of 600 °C results in the complete transformation of the Fe(Al) solid solution to a FeAl intermetallic compound. Annealing temperature significantly influenced the microstructure and microhardness of the cold-sprayed FeAl/Al₂O₃ coating. On raising the temperature to over 950 °C, diffusion occurred not only in the coating but also at the interface between the coating and substrate. The microhardness of the FeAl/Al₂O₃ coating was maintained at about 600HV_0.1 at an annealing temperature below 500 °C, and gradually decreased to 400HV_0.1 at 1100 °C.     

Formation of B2 intermetallic NiAl and FeAl by mechanical alloying

Nanostructud B2 intermetallic compounds NiAl and FeAl have been prepared by mechanical alloying (MA) the elemental powder mixtures and subsequent heating. The structural evolution during MA was monitored by in situ thermal analysis and X-ray diffraction (XRD). The final products were characterized by transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). The results show that the nanocrystalline intermetallic compound NiAl, which is difficult to disorder by milling, was synthesized directly after an exothermic explosive reaction; whereas FeAl compound was formed after a thermal process of asmilled Fe(Al) solid solution obtained through interdiffusion during MA. The large heat of formation of NiAl compound is the main driving force for the exothermic explosive reaction, and the difference in diffusivity between NiAl system and FeAl system is suggested to be the main cause of the different behaviors of formation between NiAl and FeAl compounds by MA.