热挤压变形对Al-Si复合材料组织性能的影响

利用金相显微镜、扫描电镜和万能拉伸试验机考察了用压力熔渗法制备的粒度为50~80μm的Si颗粒增强Al-Si复合材料和将其进行热挤压后的显微组织及室温拉伸性能。结果表明:以17.3∶1.0的挤压比热挤压后复合材料组织的均匀性得到了明显改善;复合材料挤压材的抗拉强度、屈服强度和伸长率较压渗材普遍提高;热挤压没有改变复合材料的断裂机制,由于挤压后颗粒分布均匀等原因,使复合材料的塑性得到改善。     

Influence of Annealing Treatments on Microstructure and Mechanical Properties of an Extruded Mg AZ31/Al 7050 Laminate

Mg AZ31/A1 7050 laminate was fabricated by co-extrusion directly from the as-cast Mg AZ31 and Al 7050 billets. The influence of annealing temperature and annealing time on microstructure and mechanical behavior of the extruded Mg/Al laminate was systematically studied. Results show that annealing treatments at 250 ℃ for 3 h or at 350 ℃ for 3 h do not result in an obvious grain coarsening of Mg layer and cannot remove the heterogeneous structure. Annealing does not vary texture in the Mg layer, a large fraction of 0002//ND and a small fraction of 0002//TD, but the intensity of component 0002//ND weakens to some extent. Lamellar microstructure in the A1 layer remains after annealing at250 ℃ for 3 h or at 350 ℃ for 3 h. High fractions of the texture components S and cube exist in the extruded sample, and annealing treatment hardly changes their fractions. Post-annealing treatment will largely reduce yield strength of extruded plate and increase plasticity slightly. The yield strength drops from 302 MPa to 206 MPa after annealing at 250 ℃ for 3 h and to 141 MPa after annealing at 350 ℃ for 3 h. The elongation to fracture increases from 1.5% to 5.4% after annealing at 250 ℃ for 3 h and to 4.8% at 350 ℃ for 3 h. The corresponding mechanism was discussed.     

ECAP结合退火工艺制备铜铝双金属复合棒材的界面组织及结合性能

利用室温4道次ECAP挤压结合退火工艺成功制备铜铝双金属复合棒材。采用扫描电镜（SEM）、能谱分析（EDS）、X射线衍射分析（XRD）和电子背散射衍射（EBSD）等方法研究铜铝双金属复合棒材结合界面微观组织,并通过剪切试验测试其界面结合强度。结果表明,在ECAP剧烈剪切作用下,铜铝双金属复合棒材首先通过塑性变形在界面处产生机械结合,后续退火热处理促进了铜铝原子之间相互扩散,在压力、温度和浓度梯度综合作用下,Cu/Al界面处形成了良好的冶金结合,界面层厚度约为1.47 μm,生成的金属间化合物主要为CuAl2;界面层内晶粒细小、均匀,为大角度晶界结构的超细晶组织,无明显的择优取向。铜铝双金属复合棒材平均剪切强度为28.94 MPa,界面结合质量良好,剪切破坏形式主要为脆性断裂。     

Texture Evolution of the Mg/Al Laminated Composite by Accumulative Roll Bonding at Ambient Temperature

以商业纯Mg、纯Al板材为初始材料,采用累积叠轧法(ARB)在室温下成功制备出Mg/Al多层复合板材。在累积叠轧过程中,复合板材中Mg层和Al组织随着循环次数的提高而细化。通过中子衍射技术对复合板材的织构进行测试后表明:在初始复合后的Al/Mg/Al三明治复合板材中,Mg层和Al层主要织构类型均为剪切织构。而在后续的累积叠轧过程当中,由于其工艺特点,导致Mg层和Al层中轧制织构组分出现,最终Mg层主要呈现出典型轧制织构而Al层则表现出以轧制织构组分为主并伴有剪切织构的混合织构类型。     

Microstructure,Mechanical Properties and Texture Evolution of Mg-Al-Zn-La-Gd-Y Magnesium Alloy by Hot Extrusion and Multi-Pass Rolling

A high-ductility Mg-8.10Al-0.42Zn-0.51Mn-1.52La-1.10Gd-0.86Y (wt%) alloy was developed by hot extrusion and multi-rolling processes. Relationships between microstructure, mechanical properties and texture evolution of the extruded and rolled alloy were investigated. The rolling process had significant effect on grain refinement of the extruded plate. The grain size reduced from 12.3 to 4.9 μm with the increasing rolling pass. With the increase in rolling pass, the proportion of dynamic recrystallized (DRXed) grains increases due to particle-stimulated nucleation, grain boundary nucleation and twin induced nucleation. In the process of multiple rolling, the basal pole gradually tilted from normal direction to transverse direction due to the asymmetric deformation and irregular grain deformation, resulting in the weakening of the base texture. The results showed that grain refinement and texture weakening were the main reasons for the good ductility of the alloy.     

6061/AZ31B/6061对称复合板的组织与力学性能研究

本文在理论分析与模拟计算的基础上,通过热轧制备了6061 Al/AZ31B Mg/6061Al对称复合板,并对其组织结构和力学性能进行了研究。首先通过经典复合板理论计算得到了复合板中6061Al的最佳包覆率,再通过有限元方法模拟得到了复合板的最佳压下率。依据理论分析和仿真计算得到的铝的最佳包覆率和复合板的最佳压下率,对6061 Al/AZ31B Mg/6061Al复合板进行组坯,并在不同轧制温度、不同压下率和不同退火时间下进行了轧制实验,最后对实验得到的复合板进行了微观组织、拉伸性能和能谱分析。结果表明,在复合板的复合界面处的镁层中发现了再结晶晶粒,且界面上形成了由Mg17Al12和Mg2Al3组成的金属间化合物;随着轧制压下率的增大,6061 Al/AZ31B Mg/6061Al复合板的拉伸强度、延伸率和界面扩散厚度显著增大;随着轧制温度的升高,复合板的拉伸强度、延伸率和界面扩散厚度也增大;而随着退火时间的增加,复合板的拉伸强度降低,但界面扩散厚度增加。     

AZ31B/Cu复合材料的扩散焊制备与界面显微组织分析

采用真空扩散焊工艺,在加热温度500℃、保温时间40 min、压力2.5 MPa、真空度1.0×10-2 Pa下制备了变形镁合金AZ31B/Cu双金属复合材料,并对复合材料界面区的微观结构和力学性能进行分析,探讨了界面反应层的形成机理。结果表明:铜在镁合金一侧富集出现晶界渗透现象。镁合金/Cu界面的组织依次为:α-Mg和沿其晶界析出相Mg17(Cu,Al)12/α-Mg/(α-Mg+Mg2Cu)共晶/Cu2Mg金属间化合物/(α-Mg+Mg2Cu)共晶/Cu(Mg)固溶体。硬度在基体两侧到界面中心区域内呈台阶式增加,最高显微硬度达到3510 MPa。Cu2Mg两侧的共晶液相出现具有先后次序,晶界渗透区与Cu2Mg之间先形成Mg-Cu共晶液相,然后共晶液相中的Mg原子穿越Cu2Mg层扩散至Cu侧,在Cu2Mg与Cu(Mg)固溶体之间形成Mg-Cu共晶液相。复合材料的界面抗剪强度达到61 MPa,剪切断裂发生在界面扩散层内,断口由撕裂棱和撕裂棱两边的大小不一的解理台阶构成。     

Al/Zn比对镁合金组织、力学性能及耐蚀性的影响

利用金相显微镜、扫描电镜、XRD、能谱仪、电子万能试验机及电化学工作站等研究了Al/Zn比对镁合金组织、力学性能及耐腐蚀性能的影响.结果表明:当Al/Zn比在1～15的范围内时,合金的相组织主要为α相和β相.在Al/Zn比等于10时,合金的抗拉强度和屈服强度分别达到最大值171.2 MPa和107.5 MPa;由极化曲线和交流阻抗曲线的测量知此时合金的耐蚀性能最好,盐水腐蚀试验测得的腐蚀速率也下降到最小值0.3 mg/(cm2·d).而伸长率则在Al/Zn比等于1时达到最大值2.02%.实验结果还表明:当Al/Zn比小于1时,合金的相组织主要为α相和τ相(Mg32(Al、Zn)49).     

超音速激光沉积制备7075/Al2O3复合涂层的显微组织及性能研究

超音速激光沉积是将超音速冷喷涂和激光辐照加热有机结合的一种新型复合材料表面处理技术,具有可制备硬质金属复合涂层、沉积效率高等优点。本工作利用超音速激光沉积技术在7B04铝合金基体上制备硬质铝合金7075与陶瓷颗粒Al₂O₃的复合涂层,系统研究激光功率对涂层的沉积特性和力学性能的影响规律。采用场发射电子显微镜(SEM)、能谱分析仪(EDS)、X射线衍射仪(XRD)和显微硬度计等仪器,对涂层的显微组织、相成分和显微硬度进行表征分析,结果表明：随着激光功率的增加,涂层的厚度、致密度、沉积效率、硬度以及涂层中Al₂O₃颗粒的分散性和相对沉积效率逐渐增加。当激光功率为600 W时,涂层的沉积厚度达1543μm,孔隙率为0.05%,涂层中Al₂O₃粉末颗粒的相对沉积效率达到峰值65%,HV硬度达到1911 MPa。当激光功率提升至900 W时,涂层的厚度、沉积效率增速放缓,孔隙率显著增加,涂层发生氧化相变,Al₂O₃粉末的相...     

Effect of Extrusion Combination Types on Microstructure and Mechanical Properties of the AZ31/GW103K Bimetallic Composite Plates

The AZ31/GW103K bimetallic composite plates were prepared by co-extrusion of different combination types (sandwich extrusion type and double semicircle extrusion type), and effects of different extrusion combination types on the microstructure and mechanical properties of bimetallic composite plates were systematically investigated. The results show that both the AZ31/GW103K bimetallic composite plates prepared by different extrusion combination types have good metallurgical bonding, and changing the combination type does not affect the thickness of the interfacial transition layer of composite plates. Compared with the monolithic AZ31 and GW103K extruded plates, co-extrusion can promote the dynamic recrystallization (DRX) of AZ31 and GW103K components in composite plates, and double semicircular extrusion type has a better promotion effect on the DRX than sandwich extrusion type. In addition, the texture of AZ31 in both monolithic AZ31 and AZ31/GW103K/AZ31 (A/G/A) plates is a typical (0002) basal texture, while that in the AZ31/GW103K (A/G) composite plate shifts to the tangent direction (TD) of extruded plate. Compared with the monolithic AZ31 extruded plate, both the yield strength and tensile strength of A/G and A/G/A bimetallic composite plates are significantly improved. The strength of A/G/A composite plate is higher than that of A/G composite plate, but its elongation is worse. Meanwhile, co-extrusion reduces the dislocation density of AZ31 and GW103K components in composite plates, and different extrusion combination types also affect the dislocation density.     

热挤压对SiCw／MB15镁基复合材料组织和性能的影响

利用SEM，TEM，X射线衍射仪等方法，研究了挤压对SiCw／MB15镁基复合材料组织和性能的影响。结果表明：热挤压后复合材料组织更加均匀，SiC晶须长轴与挤压方向平行，晶须的增强作用得到了充分的发挥，显著提高了SiCw／MB15镁基复合材料的力学性能。     

Ce及Mg对SiCp/Al复合材料界面润湿性的影响

采用液态搅拌法制备了SiCp/ZL105复合材料,并对其界面行为进行了研究.试验结果表明,表面活性元素Mg的加入能降低铝合金熔体的表面张力,进而改善SiC颗粒与铝基体间的界面润湿性,增强SiC颗粒与基体间的浸润复合;而加入富铈混合稀土后没有收到明显的效果.分析认为,Mg对铝液表面张力及其在颗粒表面润湿性的改善是通过在颗粒与熔体间引发了化学反应达到的,并非仅物理作用.在本试验条件下,Mg的加入引发了MgAl2O4在颗粒表面的生成,达到了改善界面润湿性的效果;而富铈稀土加入后,未在SiC颗粒与铝熔体间引发界面反应.     

Effect of Extrusion Temperature on the Microstructure and Mechanical Properties of Mg–5Al–2Ca Alloy

In this work, the Mg–5Al–2Ca alloy was extruded at 573, 623 and 673 K, with a ratio of 16:1 and a constant speed of 3 mm/s. Results demonstrate that the Al2Ca particle is formed in Mg–5Al–2Ca alloy. The size, amount and distribution of Al2Ca particles are influenced evidently by extrusion temperature. Unlike previous reports, the intensity of basal texture increases with increasing extrusion temperature, and the reasons are analyzed and given. Even though the average grain size increases as the extrusion temperature increased from 573 to 623 K, the YS, UTS and elongation of asextruded Mg–5Al–2Ca alloy are almost kept the same at 573 and 623 K. The reason is speculated as the balance of grain size, Al2Ca phase and texture at the two temperatures. The work hardening rate depends on extrusion temperature, and the largest θ value of Mg–5Al–2Ca alloy is obtained when the extrusion was performed at 623 K.     

Evolution,Control,and Effects of Interface in CNT/Al Composites:a Review

This review summarizes the work carried out in the field of interface study in carbon nanotube reinforced aluminum(CNT/Al) composites. Much research work has been conducted to reveal the evolution of CNT/Al interface in producing the composite with the purpose of achieving uniform distribution of CNTs and tight interfacial bonding. The effect and principles of coating were reviewed along with the illustration of ‘‘intermetallic interphases' ' design. Different roles of CNT/Al interface in structural and functional application were elucidated, and the future work that needs attention was addressed.     

退火工艺对Ni／Al复合涂层的组织和力学性能的影响

Ni/Al复合涂层经200℃以上温度退火后,可在Ni层和Al层的交界处形成Al3Ni和Al3Ni2两个稳定相以及Al9Ni2亚稳相。随着退火温度的升高,复合涂层中Ni和Al晶粒的长大使得涂层的强度和硬度降低。摩擦系数从退火前的0.36减小为退火后的0.27,涂层摩擦性能改善的主要原因是由于金属间化合物相的产生。     

CuNi复合中间层对Mg/Al扩散焊接接头组织及力学性能的影响

采用真空扩散焊接的方法获得了Mg/CuNi/Al扩散焊接接头。采用万能试验机测试焊接接头剪切强度,通过SEM,EPMA,XRD对焊接接头的显微结构和物相组成进行了分析。结果表明,Mg/CuNi/Al扩散焊接接头剪切强度随焊接温度和保温时间的增加先增加后减小,焊接温度440℃,保温时间90 min时,接头剪切强度最大值达到22.4 MPa。焊接接头主要由Al3Mg2致密组织层、Al12Mg17针状组织层、Al12Mg17和α-Mg网状组织层组成,Cu、Ni富集于网状组织层中。Mg/CuNi/Al扩散焊接接头断口主要由Al3Mg2、Al12Mg17、AlCu3、Al2Cu和Al7Cu23Ni化合物组成,断裂方式以脆性断裂为主。     

粒度和界面原子调控对SiC/Al复合材料强度的影响

SiC/Al复合材料作为一种轻质高强材料,因其优异的物理化学性能被外界广泛关注。本研究利用分子动力学方法,构建了不同SiC粒径的SiC/Al复合材料模型,根据拉伸变形模拟结果得出更小的SiC粒径有利于材料获得更高的抗拉强度。随着拉伸形变的逐渐增加,SiC颗粒在沿拉伸方向的两侧与Al基体发生分离从而产生孔隙,再从孔隙缺陷处产生位错形核并扩展至Al基体内形成塑性形变。在调节SiC/Al界面上C、Si的占位情况后,界面富Si的条件下结合更强,孔隙产生的难度增大从而对SiC/Al复合材料产生强化作用。     

Influence of Pin Offset on Microstructure and Mechanical Properties of Friction Stir Welded Mg/Ti Dissimilar Alloys

The influences of pin offset on the formation, microstructure and mechanical properties of friction stir welded joint of Ti6 Al4 V and AZ31 B Mg dissimilar alloys were investigated. The results show that sound joints are obtained at different offsets. With the offset decreasing from 2.5 to 2.1 mm, the number of Ti alloy fragments is increased, and the stir zone(SZ) is enlarged and the grains in SZ become coarser. A hook-like structure is formed at the Mg/Ti interface and its length is increased with the decrease in pin offset. The Al element has an enrichment trend at the Ti alloy side near the Mg/Ti interface when the offset is decreased, which is beneficial to the bonding of the interface. An Al-rich layer with a thickness of 3–5μm forms at the offset of 2.1 mm. All the joints fracture at the interface and present a mixed ductile-and-brittle fracture mode. The joint tensile strength is increased with the offset decreasing from 2.5 to 2.1 mm, and the maximum tensile strength of 175 MPa is acquired at the offset of 2.1 mm.     

界面互锁复合Zn层对厚板铝/镁FSW界面组织及力学性能的影响

对于铝/镁搅拌摩擦焊(FSW)接头,当母材厚度过大时,容易沿界面形成较厚的脆硬金属间化合物(IMCs),导致接头成形极其困难。本研究创新地采用界面互锁复合Zn层,研究了厚板铝/镁FSW接头界面IMCs演变和接头性能变化规律,为后续实现铝/镁FSW接头的高强度连接提供了理论及实践依据。结果表明,斜对接接头镁侧界面上部生成了平均厚度为69.7μm的低熔点共晶层(Mg+Al₁₂Mg₁₇),中部和下部生成了平均厚度为42.7和21.2μm的IMCs,该IMCs层由Al₁₂Mg_{1 7}和Al₃Mg₂组成。相比于斜对接接头,当采用界面互锁复合Zn层时,界面局部位置生成了Al-Mg-Zn相(Al₅Mg₁₁Zn₄)和Mg-Zn相(Mg Zn₂、Mg₂Zn₃)替代了原有的Al-Mg IMCs,最小IMCs厚度仅为3.9μm。拉伸结果表明,接头抗拉...     

Effect of Bonding Temperature on the Microstructures and Strengths of C/C Composite/GH3044 Alloy Joints by Partial Transient Liquid-Phase（PTLP） Bonding with Multiple Interlayers

With the use of Ti/Ni/Cu/Ni multiple foils as interlayer,carbon/carbon(C/C) composite was bonded to Nibased superalloy GH3044 by partial transient liquid-phase bonding technique.The effect of bonding temperature on the microstructures and strengths of the joints was investigated.The results showed that gradient structural multiple interlayers composed of ‘‘C–Ti reaction layer/Ti–Ni intermetallic compound layer/Ni–Cu sosoloid/residual Cu layer/Ni-GH3044 diffusion layer' were formed between C/C composite and GH3044.The shear strength of the C/C composite/GH3044 joint reached the highest value of 26.1 MPa when the bonding temperature was 1,030 °C.In addition,the fracture morphology showed that the fracture mode changed with the increase of bonding temperature.