反应自生Al_3Ni－Al_2O_3－Al复合材料

通过热力学计算，选择Ｎｉ_２Ｏ_３粉末作原材料，采用反应挤压铸造方法实现了Ａｌ与Ｎｉ２Ｏ３直接压铸反应合成Ａｌ３Ｎｉ－Ａｌ２Ｏ３－Ａｌ原位复合材料。研究了压铸工艺参数和预制块中纯Ａｌ粉的含量对反应合成复合材料过程的影响，并对反应机理做了较深入的分析。结果表明，Ｎｉ２Ｏ３与Ａｌ的反应是为高放热反应，反应是爆发式的，通过调整预制块中Ａｌ粉的体积分数控制了反应的剧烈程度，并能获得不同组成和基体含量的复合材料。对反应机理的分析表明，在Ａｌ足量的情况下，Ｎｉ２Ｏ３与Ａｌ反应合成复合材料分为两个过程，一是反应过程，即Ｎｉ２Ｏ３＋Ａｌ→Ａｌ２Ｏ３＋［Ｎｉ］；二是凝固过程，即反应后多余的Ａｌ与反应生成的［Ｎｉ］在随后冷却中的凝固过程，最终形成Ａｌ３Ｎｉ＋α－Ａｌ２Ｏ３＋Ａｌ复合材料。     

（Ni,Cr）／Al2O3复合涂层制备工艺的研究

利用粉末热喷涂法制备（Ｎｉ，Ｃｒ）／Ａｌ２Ｏ３复合涂层，采用ＸＲＤ和金相对复合涂层的相结构和相组成进行分析，并分析了喷涂工艺对金属／陶瓷系复合涂层制备的影响。实验结果表明，Ａｌ２Ｏ３粉末的沉积率和喷涂参数是影响（Ｎｉ，Ｃｒ）／Ａｌ２Ｏ３复合涂层相结构和相组成的关键。     

反应自生Al3Ni—Al2O3—Al复合材料

通过热力学计算，选择Ｎｉ２Ｏ３粉末作原材料，采用反庆挤压铸造方法实现了Ａｌ与Ｎｉ２Ｏ３直接压铸反应合成Ａｌ３Ｎｉ－Ａｌ２Ｏ３－Ａｌ原位复合材料，研究了压铸工艺数和预制块中纯Ａｌ粉的含量对反应合成复合材料过程扣影响，并对反应机理做了较深入的分析。结果表明，Ｎｉ２Ｏ３与Ａｌ的反应是为高放热反应，反应是爆发式的，通过调整预制块中Ａｌ粉的体积分数控制了反应的剧烈程度，并能获得不必基体含量的复合材料，对反应     

复合电沉积Ni－W－Al_2O_3工艺

研究了共沉积Ｎｉ－Ｗ－Ａｌ２Ｏ３复合镀层工艺，讨论了镀液中Ａｌ２Ｏ３微粒悬浮量、电镀温度、阴极电流密度及搅拌速度对镀层中Ａｌ２Ｏ３含量的影响。结果表明，选择适当的工艺参数，可以获得粒子分布均匀的Ｎｉ－Ｗ－Ａｌ２Ｏ３耐磨复合镀层。     

复合电沉积Ni—W—Al2O3工艺

研究了共沉积Ｎｉ－Ｗ－Ａｌ２Ｏ３复合镀层工艺，讨论了镀液中Ａｌ２Ｏ３微粒悬浮量，电镀温度、阴极电流密度及搅速度对镀层中Ａｌ２Ｏ３含量的影响。结果表明，选择适当的工艺参数，可以获得粒子分布均匀的Ｎｉ－Ｗ－ｌ２Ｏ３耐磨复合镀层。     

Ni3Al合金硼原子占位及晶界偏聚

依据ＬＩ２型金属间化合物八面体，四面体间隙的特点，并利用硬球模型计算了上述各类间隙的空球半径大小，发现Ｎｉ３Ａｌ合金中６Ｎｉ八面体间空球半径比其他间隙大，使硼原子在更易进入６Ｎｉ八间隙，由于富Ｎｉ－Ｎｉ３Ａｌ合金晶界比Ａｌ－Ｎｉ３Ａｌ合金有更我的６Ｎｉ八面体间隙，所以硼在富Ｎｉ－Ｎｉ３Ａｌ晶界偏聚较多，另外富Ａｌ－Ｎｉ３Ａｌ合金晶界原子间作用力比富Ｎｉ－Ｎｉ３Ａｌ合金晶界原子间作用力大，这也阻碍了     

磁控溅射铝膜的退火对膜组织结构转变的影响

利用ＳＥＭ、ＴＥＭ以及ｘ射线衍射，研究了磁控溅射Ａｌ膜的退火对膜组织 结构转变的影响。Ａｌ膜被磁控溅射在Ｎｉ基体上，所得镀膜分别经 １００℃、２００℃、 ３００℃、４００℃、５００℃、５５０℃和 ６００℃真空退火。结果表明， １００℃开始 Ａｌ膜再结晶； ４００℃开始有Ａｌ－Ｎｉ金属间化合物相生成，随温度升高，金属间化合物相的形成顺序为 Ａｌ３Ｎｉ—Ａｌ３Ｎｉ２－Ｎｉ３Ａｌ ＡｌＮｉ。薄膜的组织也由开始的细颗粒状组织转变为多边形 晶粒组织。     

Ni_3Al(IC-6)合金防护涂层抗氧化性能研究

Ｎｉ３Ａｌ合金是一种新型高温合金，ＩＣ－６合金是不含Ｃｒ而含１４％Ｍｏ的Ｎｉ３Ａｌ合金。由于高温下Ｍｏ极易氧化升华，因此为使ＩＣ－６合金在高温下可靠工作，需选择ＮｉＣｒＡｌＸ涂层作为ＩＣ－６合金的保护涂层。采用磁控溅射技术，在专用装置上按通过系统研究提出的工艺涂覆ＮｉＣｒＡｌＸ涂层，并对其抗周期氧化性能进行了研究。试验表明：ＮｉＣｒＡｌＹＳｉ涂层对ＩＣ－６合金的防护是非常有效的。     

溅射Ni3Al微晶涂层的抗氧化性能

研究了铸态Ｎｉ３Ａｌ合金及其微晶溅射涂层在１０００－１１００℃下等温氧化性能及１０００℃下的循环氧化性能，结果表明：铸态Ｎｉ３Ａｌ合金在氧化过程中形成Ａｌ２Ｏ３，ＮｉＯ和ＮｉＡｌ２Ｏ４的复杂氧化膜，微晶Ｎｉ３Ａｌ涂层在氧化过程中形成α－Ａｌ２Ｏ３和ＮｉＡｌ２Ｏ４尖晶石，不含ＮｉＯ，这种氧化膜的保护作用比含ＮｉＯ的氧化膜的保护作用好，使得其氧化增重比铸态合金小约１半，此外铸态Ｎｉ３Ａｌ合金在氧化过程     

镍硼镀层对陶瓷与金属联接的影响

采用自催化镀方法对Ａｌ２Ｏ３陶瓷表面进行３Ｎｉ－Ｂ镀层金属化处理，然后，把金属化的Ａｌ２Ｏ３分别和Ｎｉ，Ｆｅ－Ｎｉ合金组成偶对，进行了固相压力扩散焊，并通过组织分分析对界面区的固相反应进行研究。结果表明，经特殊预处理的９９％Ａｌ２Ｏ３陶瓷，其表面镀层Ｎｉ－Ｂ型基体的结合强度可达２５０ＭＰａ以上，镀层呈非晶态，而热处理可完全晶体化。Ｎｉ－Ｂ／Ｎｉ（Ｆｅ－Ｎｉ）对。界面消失，成分完全均匀；Ａｌ２Ｏ３／     

The mechanical properties related to the dominant microstructure in the weld zone of dissimilar formed Al alloy joints by friction stir welding

The joint properties of dissimilar formed Al alloys, cast Al alloy and wrought Al alloy, were examined with various welding conditions. Friction stir welding method could be applied to join dissimilar formed Al alloys which had different mechanical properties without weld zone defects under wide range of welding condition.The weld zone of dissimilar formed Al alloy exhibited the complex structure of the two materials and mainly composed of the retreating side material.The mechanical properties also depended on the dominant microstructure of the weld zone with welding conditions. The different mechanical properties of the weld zone with welding conditions were related to the behavior of the precipitates of wrought Al alloy and Si particles of cast Al alloy. The higher mechanical properties of the weld zone were acquired when a relatively harder material, wrought Al alloy, was fixed at the retreating side.     

ZG 1Mn19Ni3Al 铸焊结构低温性能研究

通过化学成分设计和金相组织设计，开发了一种适用于与１６Ｍｎ钢组成铸焊结构的新铸钢ＺＧ１Ｍｎ１９Ｎｉ３Ａｌ。研究了这两种材料组成的焊板在常温、低温（－１９６℃）下的力学性能和冲击断口形貌。试验结果表明，夹杂物和焊接线能量对其低温冲击韧性有着显著的影响。具有γ＋ε双相组织的ＺＧ１Ｍｎ１９Ｎｉ３Ａｌ钢用于低温（－１９６℃）铸焊结构中时要注意钢水精炼和采用适当的焊接线能量     

Molecular dynamics simulation of the effect of surface roughness and pore on linear friction welding between Ni and Al

Atomic model of Ni–Al linear friction welding is established by molecular dynamics simulation. The effect of surface roughness on linear friction welding and the rules of pore closure are investigated. The simulations results show that rough surfaces are gradually flattened during the friction process. The rough surface of the harder material (Ni) may influence the final structure of the weld. Pores near the interface is closed after linear friction welding. Pore closure in Al slab occurs in friction process by atom diffusion, while it takes place in Ni slab in forging stage mainly by deformation of the interface.     

Cr7C3 / Ni3Al 复合材料制备过程中碳化铬的溶解再析出行为

将真空常压烧结方法制得的Cr₃C₂-Ni₂Al 复合焊丝堆焊于碳钢表面。分析表明, 在堆焊过程中, 利用氩弧物理热和Ni-Al 反应热, Ni 与Al 化合反应生成Ni₃Al 金属间化合物, Cr₃C₂ 则发生分解, 除少部分[ C]与[Cr ]固溶于Ni₃Al 基体中外, 大部分反应析出更稳定的Cr₇C₃ 相, 其尺寸取决于堆焊层中不同区域的冷却环境,较为均匀地分布于Ni₃Al 基体中。由于Cr 在Ni₃Al 中的固溶度远大于C , 加之Cr₃C₂ 转化为Cr₇C₃ 也造成部分富余的C , 结果造成在该Ni₃Al 表面强化材料焊层中形成石墨相, 其密度轻、熔点高, 主要偏聚于焊层表层。Cr₇C₃ / Ni₃Al 复合材料的室温、高温硬度远高于传统高温耐磨材料Stellite 合金, 该材料有望成为一种新型的高温耐磨表面强化材料。      

碳化物特性对Ni3Al基表面强化复合材料组织与性能的影响

将真空常压烧结的方法制得的Cr3C2-Ni-Al和WC-Ni-Al复合焊丝氩弧堆焊于碳钢表面时,利用氩弧物理热和Ni-Al反应热,促使碳化物硬质颗粒与自生成的Ni3Al金属间化合物基体复合.XRD分析表明,在堆焊过程中两种焊丝中的Ni,Al均化合反应生成Ni3Al金属间化合物.微观组织与硬度试验表明,受各自物理特性(密度、熔点)的影响,两种碳化物硬质相在Ni3Al基体中分布均匀程度不同,其强化效果也迥异:WC仍以原始的大颗粒形态偏聚于焊层层间界面处,而起不到弥散强化作用;Cr3C2则发生分解,并反应析出条块状的Cr7C3相,均匀分布于Ni3Al基体中,很好地强化了基体材料.Cr7C3/Ni3Al复合材料的室、高温硬度远高于传统高温耐磨材料stellite合金.该合金有望成为一种新型的高温耐磨表面强化材料.     

Laser welding of Ti–6Al–4V to Nitinol

Formation of brittle intermetallic phases in addition to different thermal expansion coefficients associated with dissimilar welding leads to the formation of transverse cracks in weld metal and eventually restricts widespread applications of dissimilar joints. Therefore, joining technology should be expanded in field of dissimilar welding in order to solve its difficulties. In the present study, an experimental work with pulsed Nd:YAG laser was performed for dissimilar welding of Ti–6Al–4V and Nitinol. Autogenous welding of these two alloys resulted in joints with poor strength and ductility due to the formation of transverse cracks in the weld metal. Therefore, the chemical composition of the weld metal has to be modified in order to reduce the formation of brittle phases and eliminate subsequent cracking. In this work, this was done by insertion of a copper interlayer with a thickness of 75 μm between the base metals. The results indicated that insertion of copper interlayer has a great influence on the reduction of the amount of Ti₂Ni brittle intermetallic phase, elimination of transverse cracks through the weld metal and eventually improvement of mechanical properties of the joints. Insertion of copper interlayer was very useful since it altered the cracked autogenous joint to a joint which could withstand a tensile stress of 300 MPa.     

The influence of adhesive on the Al alloy in laser weld bonding Mg–Al process

Laser weld bonding is a new welding technology, being used to join Mg–Al alloys. The penetration depth of LWB Mg–Al joint was larger than that in simply laser welding joint in same welding parameters. The temperature at the edge of the Al fusion zone in LWB Mg–Al joint was higher than that in laser welding joint, which was measured through the thermal couples. The laser-introduced plasma in LWB Mg–Al process is observed by the high-speed camera, which is different from that in laser welding process. The surface temperature and state of the Al alloy were changed because of the addition of the adhesive, thus the laser absorptive of Al alloy was increased in LWB process, comparing with that in laser welding process; and the decomposition of the adhesive would make a depression in the Al fusion zone, which would be beneficial to the formation of keyhole welding in LWB Mg–Al joint.     

Single-sided laser beam welding of a dissimilar AA2024–AA7050 T-joint

In the aircraft industry double-sided laser beam welding of skin–stringer joints is an approved method for producing defect-free welds. But due to limited accessibility – as for the welding of skin–clip joints – the applicability of this method is limited. Therefore single-sided laser beam welding of T-joints becomes necessary. This also implies a reduction of the manufacturing effort. However, the main obstacle for the use of single-sided welding of T-joints is the occurrence of weld defects. An additional complexity represents the combination of dissimilar and hard-to-weld aluminium alloys – like Al–Cu and Al–Zn alloys. These alloys offer a high strength-to-density ratio, but are also associated with distinct weldability problems especially for fusion welding techniques like laser beam welding. The present study demonstrates how to overcome the weldability problems during single-sided laser beam welding of a dissimilar T-joint made of AA2024 and AA7050. For this purpose a high-power fibre laser with a large beam diameter is used. Important welding parameters are identified and adjusted for achieving defect-free welds. The obtained joints are compared to double-sided welded joints made of typical aircraft aluminium alloys. In this regard single-sided welded joints showed the expected differing weld seam appearance, but comparable mechanical properties.     

交流电弧超声对SiC_p/6061Al焊接接头的作用机理研究

为了改善SiCp/6061Al的焊接性能,在其焊接过程中引入了电弧超声技术.应用自主研制的交流电弧超声等离子焊接设备,以自制的Al-15Ti-3Si药芯焊丝为填充材料,在不同频率的电弧超声作用下对SiCp/6061Al进行了等离子弧原位焊接,研究了电弧超声对焊接接头的作用机理.实验结果表明：电弧超声可使新生Al3Ti相...     

钛合金板与不锈钢网扩散焊接技术研究

分析了钛和铁异种金属焊接存在的问题。根据真空扩散焊接过程和特点,详细研究了TC4钛合金板与00Cr18Ni13不锈钢网的直接真空扩散焊接工艺。焊缝显微分析表明,无论焊接规范大小,无法避免异质接头内脆性金属间化合物相的生成,通过优化选择扩散焊工艺,将焊缝中金属间化合物减小到最低程度,获得了较满意的焊接效果。