搅拌摩擦加工制备碳纳米管增强铬锆铜基复合材料的工艺探索

本文用搅拌摩擦加工的方法成功制备了碳纳米管增强铬锆铜基复合材料,并对制得的复合材料的组织、硬度进行了分析。结果表明,在搅拌头旋转速度为750r／min,挤压速度为30mm／min时能获得良好成型的复合材料,复合区的晶粒大小较母材发生了明显的细化,硬度得到了显著的提高。     

搅拌摩擦加工制备NiTip/WE43镁基复合材料

本研究提供了一种采用搅拌摩擦加工（FSP）制备NiTi颗粒增强WE43镁基复合材料的有效手段。采用SEM结合EDS对FSP试样的微观结构进行了研究,采用XRD进行了物相分析。结果表明,制备的复合材料具有形状记忆效应。较低的加工温度有效地阻止了NiTi颗粒与Mg基体在FSP过程中的界面反应。无论粒径大小,在FSP后,NiTi颗粒都均匀分布在Mg基体中。此外,与Mg基体相比,NiTi/WE43复合材料的屈服强度、极限拉伸强度和延伸率分别降低了33%、12%和18%。随着加入的NiTi颗粒尺寸的增大,该复合材料拉伸强度和延伸率均降低。复合材料的失效机理是颗粒之间的界面开裂以及增强颗粒的断裂。     

搅拌摩擦加工AZ31镁合金的超塑性

对搅拌摩擦加工AZ31镁合金的微观组织和拉伸力学行为进行了研究。结果表明,通过搅拌摩擦加工,热轧AZ31板材的平均晶粒尺寸由92.0μm细化到11.4μm。搅拌摩擦加工板材在高温下具有优异的塑性,伸长率在温度为723K和应变速率为5×10-4s-1的条件下达到1050%。该材料还具有高应变速率超塑性,在723K和1×10-2s-1的条件下伸长率达到268%。在相同实验条件下,母材由于晶粒尺寸粗大,没有显示出超塑性。     

纳米SiCw增强铝基复合材料的搅拌摩擦加工制备

用搅拌摩擦加工法制备纳米SiCw增强ZL114A铝基复合材料,并对其组织及性能进行分析.结果表明,在30 mm×6mm形成了结构致密,无明显疏松、孔洞的搅拌摩擦复合区,复合区晶粒细小,搅拌摩擦中心区SiCw分布较均匀.该复合材料经T6热处理后强化效果不明显,SiCw主要起韧化作用,搅拌摩擦中心区硬度及抗拉强度略有下降,但伸长率得到改善,比基材提高111.4％.     

搅拌摩擦加工制备碳纤维增强H62黄铜基复合材料探索

文中选用碳纤维为增强相,通过在H62黄铜板上钻孔添加碳纤维的方式,采用搅拌摩擦加工的方法制备碳纤维增强H62黄铜基复合材料,研究了焊接速度和碳纤维的复合量对复合材料成形和性能的影响,进行了正交变量试验.结果表明:在焊接速度为40 mm/min,添加碳纤维的孔深为1.5 mm时,碳纤维在复合材料中分布比较均匀,复合材料中...     

搅拌摩擦加工制备铝基复合材料组织性能研究

采用搅拌摩擦加工法制备铝基SiC复合层,研究不同加工道次下SiC颗粒在复合层中的分布形态,并对复合层的组织形貌和显微硬度进行分析。结果表明:加工次数的增加,有利于复合层中SiC颗粒的均匀分布,经4道次搅拌摩擦加工后复合层中SiC颗粒分布均匀,基体金属组织中粗大Si相和枝晶完全消失,组织被明显细化。增强相SiC颗粒的加入使复合层显微硬度得到提高,4道次加工后搅拌摩擦中心区显微硬度最高值为71 HV,较基体金属(45HV)提高了26 HV,搅拌摩擦区的显微硬度平均值为68HV,为基体金属显微硬度(45HV)的1.5倍。     

碳酸钠对搅拌摩擦加工AZ31镁合金缓蚀性能的影响

通过搅拌摩擦加工(FSP)手段,对3 mm厚的AZ31镁合金板材作表面加工处理.然后在质量分数为5%的NaCl腐蚀溶液中添加不同浓度的碳酸钠作为缓蚀剂,通过动电位极化曲线以及交流阻抗(EIS)测试,研究了室温下该缓蚀剂对镁合金母材及搅拌摩擦加工处理镁合金电化学行为的影响.结果表明,添加缓蚀剂后,FSP镁合金及母材的腐蚀电流密度均减小,极化电阻及电荷转移电阻均增大,而且FSP镁合金的缓蚀效率要优于母材的缓蚀效率,且随浓度的增加而增加,碳酸钠是一种有效的无机缓蚀剂,并且其缓蚀作用效果与金属表面状态密切相关.     

搅拌摩擦加工碳纳米管增强7075铝基复合材料的疲劳性能

采用搅拌摩擦加工方法制备了碳纳米管增强7075铝基复合材料,研究了复合材料显微组织和疲劳性能。结果表明:复合材料晶粒细小,增强相碳纳米管在基体中分散均匀。随碳纳米管体积分数的增加,碳纳米管在基体中的分散程度降低。复合材料的疲劳性能高于基材,且随着碳纳米管含量的增加,复合材料的疲劳性能逐渐提高,但发现其抗拉强度呈现逐渐减小的趋势。复合材料中存在少量的大尺寸金属间化合物、非金属夹杂、片状氧化物等缺陷对复合材料的疲劳性能造成不利影响。     

搅拌摩擦加工AZ31细晶镁合金超塑性行为研究

借助搅拌摩擦加工工艺制备了AZ31细晶镁合金,研究对比了原始母材和各种晶粒尺寸细晶镁合金的超塑性行为。结果表明：AZ31板材平均晶粒尺寸由7.67μm细化到0.94μm~3.21μm。在450℃,应变速率5×10-4/s-1时原始母材最大延伸率为630%,搅拌摩擦加工后的材料最大延伸率为405%,说明晶粒尺寸与超塑性性能没有线性关系。超塑性变形机制主要是晶界滑移,孪生对变形也有一定影响。断裂机制是晶间微小空洞的形成、长大和连接。     

搅拌摩擦加工法制备碳纳米管增强铜基复合材料工艺探索

本文采用搅拌摩擦加工法制备了碳纳米管增强铜基复合材料,研究了试验工艺参数（搅拌头的倾斜角度、旋转速度和挤压速度）对复合材料成形的影响。结果表明：在进行单一变量试验发现,在挤压次数为3次,倾斜角度为3°,旋转速度为750r／min,挤压速度为30mm／min时,复合材料的成形较好,碳纳米管在复合材料中较均匀地分布,复合材料中无明显的疏松和孔洞等缺陷出现。     

Characterization of aluminum based functionally graded composites developed via friction stir processing

Al/SiC functionally graded material (FGM) was developed through a novel multi-step friction stir processing (FSP) method. SiC particles with a mean size of 27.5 μm were embedded in the groove on the 6082-Al plate. To create a graded structure over a predefined value, FSP was carried out with three tools with different pin lengths and with varying volume fractions of SiC particles. The structure was formed by passing tools with 1−3 passes with a constant rotational and traveling speeds of 900 r/min and 20 mm/min, respectively. The experiments were conducted at room temperature. Microstructural features of functionally graded (FG) samples were examined by using scanning electron microscopy (SEM) and 3D light microscopy. Mechanical properties in terms of wear resistance and microhardness were thoroughly assessed. The results indicate that the increase in FSP pass number causes more uniform SiC particle dispersion. The microhardness values were impacted by the number of passes and improved by 51.54% for Pass 3 when compared to as-received 6082-Al. Wear resistance of Al/SiC FG samples was found to increase as a result of the addition of SiC particles.     

搅拌摩擦加工Al-Pb表面复合材料的微结构和织构

采用搅拌摩擦加工(FSP)方法制备Al-Pb表面复合材料,以提高其减摩抗磨性能,使用SEM、EBSD、纳米压痕仪和显微硬度计等分析其微观组织、织构和硬度分布。结果表明:使用FSP方法制备Al-Pb表面复合材料,Pb颗粒受到重力和搅拌作用,主要分布于盆状搅拌加工区的底部。塑性金属对流形成的洋葱环结构中,存在富Pb片层和形变铝基体片层。富Pb片层内的Pb颗粒,起到了良好的细化晶粒作用。形变铝基体片层分布有少量直径约100 nm的新生Pb粒。受到细晶强化作用影响,富Pb颗粒区的硬度显著高于形变铝基体。加工区底部的SZ-AS区形成强Cube再结晶织构;SZ-RS区形成Cube织构和少量Brass织构;CSZ区的Cube织构较少,{111}织构增强;上部的AS区形成强Goss织构,RS区织构相对随机。     

搅拌摩擦加工制备石墨烯/Al复合材料的界面微观结构

以纯净石墨烯为原料,采用搅拌摩擦加工法制备石墨烯/Al复合材料,主要通过透射电镜等手段观察分析复合材料石墨烯?Al的两种界面,即石墨烯平面?Al、石墨烯边缘?Al的界面微观结构,并对界面形成机制进行了分析。结果表明:石墨烯平面?Al界面清晰,是典型的机械结合界面;而石墨烯边缘?Al界面存在过渡,且在其附近偶尔还发现Al4C3的分布,此区域主要以扩散结合并可能具有部分反应(扩散+部分反应)的界面形式存在。复合材料的界面形成机制与石墨烯不同位置的C原子活性有关,平面内C原子的大π共轭结构使其高度惰性,形成机械结合界面;而搅拌摩擦加工过程对石墨烯的破坏主要发生在边缘,由于C—C键合被破坏,石墨烯边缘活泼的C原子与Al基通过C—Al原子的相互作用而形成扩散+部分反应的过渡界面。     

搅拌摩擦加工原位反应制备Al3Ti-Al表面复合层

通过在铝合金1100-H14表面加工矩形凹槽并添加微米级钛粉再进行搅拌摩擦加工(friction stir processing,FSP)的方法,在铝合金表面获得Al3Ti-Al复合层.采用扫描电镜(SEM),能谱分析(EDS)以及X射线衍射(XRD)对表面复合层微观结构及相组成进行了分析,并对复合层的显微硬度进行了检测.结果表明,在FSP强烈的热、力耦合作用下,钛粉产生了碎化,破碎后的钛颗粒与铝产生快速原位反应,生成微米和亚微米级Al3Ti颗粒,残留的钛颗粒和细小的Al3Ti颗粒一同均匀地分布于铝合金基体中,从而使得铝合金表面的硬度得到提高,其平均值达到了71.39HV,为基体硬度的2.1倍.     

《搅拌摩擦加工制备GNPs/Al复合材料的微观结构与力学性能》

本文以纯铝为基体,利用搅拌摩擦加工(FSP)制备GNPs/Al复合材料,研究了复合材料基体组织、增强相与界面等微观结构与力学性能,探讨了其增强机理。结果表明,添加GNPs并经FSP后复合材料基体晶粒得到明显细化且晶界由小角度为主转变为大角度为主;FSP制备过程致使GNPs片层一定程度剥离的同时,较大片径的GNPs被破碎而形成众多边缘缺陷,使其易发生Al-C原子扩散,结果在GNPs边缘与基体形成界面过渡;GNPs加入量约1.8vol%时,复合材料的屈服强度和抗拉强度达到72MPa和147MPa,较同等条件FSP的基体分别提高了89.5%和79.3%,理论计算界面载荷传递、Orowan和细晶强化依次是复合材料的主要增强机制;随着GNPs加入量的增加,复合材料屈服强度实验值与理论值的增长趋势一致,且偏差也略有提高,但可能因GNPs在复合材料中的杂乱排布,界面载荷传递强化不能充分发挥,实际的复合材料屈服强度与理论值尚有差距。     

Surface modification of aluminium by friction stir processing

In this study, SiC particles were incorporated by using Friction Stir Processing (FSP), into the commercially pure aluminium to form particulate surface layers. Samples were subjected to the various tool rotating and traverse rates with and without SiC powders. Microstructural observations were carried out by employing optical microscopy of the modified surfaces. Mechanical properties like hardness and plate bending were also evaluated. The results showed that increasing rotating and traverse rate caused a more uniform distribution of SiC particles. The hardness of produced composite surfaces was improved by three times as compared to that of base aluminium. Bending strength of the produced metal matrix composite was significantly higher than processed plain specimen and untreated base metal.     

聚四氟乙烯对搅拌摩擦加工制备Al-Ni复合材料均匀性的影响

采用搅拌摩擦加工技术制备了Al-Ni系金属间化合物增强铝基复合材料,通过SEM、XRD对复合材料的微观结构及相组成进行了分析,研究在原材料中添加聚四氟乙烯对搅拌摩擦加工制备复合材料中增强相含量及分布均匀性的影响,并对增强相形成的物理模型进行了探讨。结果表明:添加聚四氟乙烯可以显著改善Al-Ni复合材料的均匀性;加入聚四氟乙烯后会阻隔Ni粉的团聚,致使Ni与Al的接触面增大,从而增大了Ni与Al的反应界面,导致反应程度增大,Al_3Ni金属间化合物生成量增多。     

Functionally graded materials produced by friction stir processing

An investigation was conducted in order to produce aluminium based functionally graded MMC reinforced by SiC ceramic particles with median size of 118.8, 37.4 and 12.3 μm. AA5083 aluminium alloy plates in the H111 and partially annealed conditions were processed. Several strategies for reinforcement were investigated and its influence on the particle distribution and homogeneity was studied. A square shaped groove packed with reinforcement particles of SiC was studied and it was seen that it was more effective when the groove was placed under the probe. If the groove was placed outside the probe interaction area, but within the shoulder influence area, insufficient dispersion of particles was observed. Small particles lead to higher concentration along the bead surface and to smooth fraction gradients both in depth and along the direction parallel to the surface. The thickness of the reinforced layer depends of particle size within the parametric conditions and the tool geometry used in this investigation.