原位自生Al—4Cu—0.8Mg／TiGp复合材料半固态挤压的组织与力学性能

本文对自生Al-4Cu-0.8Mg/TiCp复合材料采用T4和T6两种热处理制度，测试了该材料的σb、σs、E和δ。通过SEM观察和分析了半固态挤压原位自生Al-4Cu-0.8Mg/TiCp复合材料的显微组织和断口形貌。结果表明：在T6状态下ω（TiCp）为15％的复合材料的σb、σs、E分别达到540MPa、430MPa、92GPa,δ为3．2％，断裂形式为韧性断裂，由此可以认为自生TiCp/2024复合材料具有优良的综合力学性能。     

焊前热处理状态对SiC_p/Al-Cu-Mg复合材料搅拌摩擦焊接头微观组织和力学性能的影响

在工具转速800 r/min,焊接速度100 mm/min的工艺参数下,对6 mm厚的15%SiCp/2009Al(体积分数)板材在软态(固溶态)和硬态(自然时效态)下进行搅拌摩擦焊接,均获得致密无缺陷的接头.结果表明,样品原始状态对焊核区的晶粒尺寸、析出相(Al2Cu)分布和硬度均影响不大.2种样品的热影响区均存在2个低硬度区.靠近焊核区的低硬度区在焊接热循环过程中温度较高,2种样品均发生Al2Cu相的粗化,硬度值相同;但在远离焊核区的低硬度区,固溶态样品不发生固溶原子团簇回溶,该区域的硬度略高于自然时效态样品,并且位置更靠近焊核中心.2种接头横向拉伸时均断裂在靠近焊核的低硬度区,强度基本相同,可达母材强度的83%.这表明,固溶软态下进行15%SiCp/2009Al板材的搅拌摩擦焊接,可以取得常规时效硬态下焊接的效果,有助于扩大焊接工艺窗口,减少焊接工具磨损.     

搅拌铸造SiC_p/A356复合材料的显微组织及力学性能

采用搅拌铸造技术制备质量分数为15%的SiCp增强A356铝基复合材料,并对所制备的复合材料进行后续热挤压变形。通过金相观察(OM),扫描电镜(SEM)及力学性能测试等手段,对该复合材料显微组织与力学性能进行了研究。结果表明,所制备的复合材料铸态组织中,SiCp较均匀地分布于基体中,SiCp与Al界面处存在Si原子的富集;热挤压变形后,显微气孔等铸造缺陷明显减少,材料致密度显著提高,SiCp沿热挤压方向呈流线分布特征,颗粒均匀分散性明显提高;采用535℃×5h固溶+180℃×5h时效处理后,热挤压棒材的力学性能为:σs=370MPa,σb=225MPa,δ=5.3%,时效后析出强化相大小约为200nm,且弥散分布于基体中;断口分析表明,SiCp/A356铝基复合材料的断裂主要是由基体的塑性断裂及SiCp的断裂导致的。     

搅拌铸造SiC_p/2024铝基复合材料的显微组织与力学性能

利用搅拌铸造?热挤压工艺制备SiCp/2024铝基复合材料板材,研究该复合材料铸态、热挤压态和热处理态的显微组织及力学性能。结果表明:SiC颗粒较均匀地分布于铸锭中,大部分SiC颗粒沿晶界分布,少数颗粒分布于晶内,晶界粗大的第二相呈非连续状分布;复合材料经热挤压变形后,显微孔洞等铸造缺陷明显消除,破碎的晶界第二相及SiC颗粒沿热挤压方向呈流线分布,复合材料的强度和塑性显著提高;对热挤压板材进行(495℃,1h)固溶处理+(177℃,8h)时效处理后,其抗拉强度达430MPa,此时的主要析出强化相为S′(Al2CuMg);热挤压变形有利于改善SiC颗粒与基体合金的界面结合,热处理SiCp/2024铝基复合材料的主要断裂方式为基体合金的延性断裂、SiC颗粒断裂和SiC/Al的界面脱粘。     

SiCp/6061Al复合材料等离子弧焊工艺参数对焊缝组织及性能的影响

采用等离子弧焊接工艺研究铝基复合材料SiCp/6061Al的焊接性,借助X射线衍射、扫描电镜等手段分析接头组织,着重探讨了在填加和不填加合金化填充材料Ti的情况下,焊接电流、焊接速度对焊缝显微组织及焊接接头力学性能的影响机理,研究表明,在未填加材料Ti时,焊接工艺参数的改变并不能抑制有害相Al4C3的生成,只能改变其尺寸和数量;在填加填充材料Ti时,焊缝熔池中增强相的种类及分布是影响焊接接头性能的主要因素;适当调整焊接工艺参数有利于焊缝中心形成完全以新生颗粒TiC,TiN和AlN为增强相的完全原位反应区;同时减小新旧增强相共存区域的宽度,并消除增强相SiC颗粒的偏聚现象,从而提高了焊接接头的力学性能.     

搅拌工艺对SiCp／ZL109复合材料微观组织的影响

采用熔液搅拌法制备SiC颗粒增强ZL109铝合金基复合材料。通过对搅拌速度、搅拌温度和搅拌时间等参数对复合材料显微组织的影响试验分析,找出搅拌法制备复合材料过程中工艺参数的影响规律。     

纳米SiC颗粒增强镁基复合材料半固态搅拌法制备工艺优化

采用半固态机械搅拌铸造法,制备了增强体平均粒径50 nm的Si C颗粒增强镁基复合材料(n-Si Cp/Mg9Al),分别对不同质量分数纳米颗粒、不同搅拌时间和不同搅拌温度时,复合材料的微观组织和力学性能进行了研究。结果表明,随着Si C含量的增加,合金基体组织先细化后又出现变粗的现象,适当延长搅拌时间能更有效地细化组织,在较低温度下搅拌可以更明显地细化复合材料的微观组织。合金抗拉强度随着Si C含量的增加先增加后降低,在Si C含量为1.5%时最好,为198 MPa。在含量为2%时又有所降低,但是高于不加Si C时。搅拌时间为15 min时,复合材料的屈服强度、抗拉强度较之基体分别提高了12.8%、22%,断后伸长率由基体合金的2%提升到4%。继续延长搅拌时间到30 min,材料的室温拉伸性能出现明显恶化。不同搅拌温度下Si Cp/Mg9Al纳米复合材料与铸态Mg9Al合金相比其室温拉伸性能有明显提高,搅拌温度为600℃的Si Cp/Mg9Al纳米复合材料的室温拉伸性能最好,其屈服强度、抗拉强度和断后伸长率分别为106 MPa、155 MPa和4%。     

球磨工艺对Mg2B2O5w/6061Al基复合材料微观组织演变及力学性能的影响

采用粉末热挤压法制备了硼酸镁晶须增强铝基复合材料,对球磨工艺参数、粉末特性及热挤压态复合材料间的相互关系进行了研究。研究结果表明,在球磨过程中,增强体晶须的添加促进了基体合金的变形,加快了铝粉颗粒的焊合与断裂过程的发生。在球磨过程中,经过适当时间的高速球磨后,铝合金基体晶粒尺寸减小,增强体晶须在基体中的分布得到显著改善,从而使热挤压态复合材料力学性能得到大幅度的提高。     

SiC含量对铝基复合材料组织与力学性能的影响

采用半固态-液态搅拌铸造法制备了Si C颗粒增强铝基复合材料。研究了Si C颗粒含量(质量分数分别为0、5%、10%、15%和20%)对铝基复合材料组织及力学性能的影响。结果显示:添加少量Si C颗粒时,Si C颗粒在基体中分散均匀;当Si C质量分数达到15%时,Si C颗粒团聚较严重。随着Si C颗粒含量的增加,复合材料的硬度和抗拉强度先升高后降低。原因是Si C颗粒的位错强化作用,使得铝基复合材料的力学性能得到提升。随着Si C颗粒含量的增加,与界面结合良好的含Mg相数量减少,并且Si C颗粒团聚严重,铝基复合材料的力学性能降低。     

搅拌工艺参数对SiC_p/Al复合材料颗粒分布的影响

采用机械搅拌法制备了不同SiCp含量Al基复合材料,研究了搅拌参数对颗粒分布的影响。通过SEM和XRD对SiCp在基体中的分布及复合材料的物相成分进行了分析。结果表明,搅拌桨直径为60mm,叶片倾角为30°,搅拌速度为680r/min时制得的复合材料,其SiCp分布均匀且无明显气孔生成。在慢冷条件下浇注的复合材料无明显颗粒沉降现象发生。物相分析显示有MgAl2O4、Mg2Si生成,没有发现有害界面反应产物Al4C3。     

Effects of whisker surface treatment on microstructure and properties of Al_(18)B_4O_(33w)/6061Al composites

6061Al matrix composites reinforced by ZnO-coated Al18B4O33 whiskers were fabricated by a semi-solid mechanical stirring technique.The effects of ZnO coating on interfacial reaction between whiskers and matrix and the tensile properties of the composites were investigated.Tensile tests on composites were performed at room temperature,and microstructures were observed by scanning electron microscopy(SEM).The results show that the surface treatment of whiskers could reduce interfacial reaction effectively,improve the wettability between whiskers and matrix and enhance the tensile properties of the composites obviously.In addition,semi-solid stirring parameters were also under preliminary study.The stirring parameters were determined by the distribution of whiskers in the composites.The composites with homogeneously distributed whiskers were fabricated by semi-solid stirring at 610 ℃ for 30 min.     

热处理对挤压铸造TiB2P/6061Al复合材料组织与性能的影响

采用挤压铸造法制备了不同体积分数的TiBzv／6061Al复合材料，利用扫描电镜、透射电镜、硬度计、三点弯曲等手段对复合材料的组织与力学性能进行了研究，分析了热处理工艺对其组织性能的影响。结果表明：不同的热处理条件下TiB2P／6061Al复合材料的组织不同：退火态时观察到再结晶晶粒和少量位错：时效态时观察到大量的位错和析出相，界面产物尺寸比退火态时相对大些，且在界面附近的基体中存在明显的无析出区。热处理状态对弹性模量的影响不大，但对材料的硬度和抗弯强度影响较大。45％TiB2v／6061Al复合材料时效处理后硬度和抗弯强度分别比退火态时提高了40％和23％。     

Microstructure and properties of mechanical alloying particles reinforced aluminum matrix composites prepared by semisolid stirring pouring method

Aluminum matrix composites reinforced with mechanical alloying particles(SiC_p) were fabricated by the semisolid stirring pouring method. The inf luence of mechanical alloying particles and Mg on the microstructure and mechanical properties of the composites was investigated by means of optical microscopy(OM), X-ray diffraction scanning(XRD), electron microscopy(SEM) and energy dispersive spectroscopy(EDS). Results show that the addition of Mg converts the agglomerate mechanical al oying particles in ZL101 matrix composites into dispersed distribution in ZL101-Mg matrix composites, large matrix grains into f ine equiaxed matrix grains, and eutectic phase into f ine particles. So the mechanical properties of ZL101-Mg matrix composites are better than those of ZL101 matrix composites. The mechanical properties of ZL101/ZL101-Mg matrix composites are gradually increased with the increase of the volume fraction of mechanical alloying particles. When the volume fraction of mechanical alloying particles is 3%, the Vickers hardness and ultimate tensile strength of the ZL101/ZL101-Mg matrix composites reach their maximum values.     

Effects of Mg content on microstructure and mechanical properties of SiCp/Al-Mg composites fabricated by semi-solid stirring technique

10%(volume fraction) SiCp/Al-Mg composites with different Mg contents were successfully fabricated by semi-solid mechanical stirring technique under optimum processing conditions.Effects of Mg content on microstructure and mechanical properties were studied by scanning electron microscopy(SEM),X-ray diffractometry(XRD) and transmission electron microscopy(TEM).The results indicate that SiC particles disperse homogeneously in Al-Mg matrix and interfacial reaction between Al matrix and SiC particles is effectively controlled.Distribution of SiCp reinforcement and interfacial bonding are improved by adding Mg.Additionally,the mechanical properties of composites are remarkably improved with the Mg content increasing.     

Al2O3p/Al复合材料中颗粒粒径与形态对组织和性能的影响

选用 5 .0和 0 .15 μm两种粒径的Al2 O3 颗粒 ,制备了Al2 O3 体积分数为 40 %的铝基复合材料。利用透射电镜对两种复合材料拉伸前后的组织进行观察 ,结果表明 :5 μm尖角形Al2 O3 颗粒增强复合材料的铸态组织中存在高密度的位错 ,这主要是由于热错配应力引起的 ;0 .15 μm椭球形Al2 O3 颗粒增强复合材料的铸态组织中几乎观察不到位错 ,这与颗粒细小且为等轴状、分布弥散、界面附近应力分布均匀等因素有关。对拉伸断口附近显微组织的观察表明 ,前者基体中位错进一步增殖 ,后者则存在明显的位错环。室温拉伸结果表明亚微米Al2 O3p/Al复合材料中的这种微观组织有利于材料强度和塑性的提高     

钛对碳纳米管增强铝基复合材料组织与性能的尺寸效应

通过粉末冶金的方法,制备了致密和较高强度的CNT/Al复合材料,并系统地研究了在制备粉末阶段时引入不同粒径的钛粉后,对复合材料的组织结构与力学性能的影响。结果表明,在一定范围内,钛颗粒尺寸与制备的CNT-Ti/Al复合材料力学性能成反比。当加入的钛颗粒粒径为80 nm时,CNT-Ti/Al复合棒材力学性能最佳。其主要原因包括两个方面:一是钛颗粒有助于碳纳米管的分散,同时自身作为一种第二相强化基体;二是制备过程的热反应,使复合材料组织中生成了一种核壳结构,极大地增强了其界面结合与碳纳米管的载荷转移。     

SiC_p/2024铝合金复合材料粉末混合半固态挤压法制备

研究了SiCp/ 2 0 2 4铝合金复合材料的粉末混合 半固态挤压成形工艺及所制备材料的组织和界面特征。不同温度下半固态挤压的挤压力与位移曲线表明 ,半固态挤压过程的成形力低且稳定。SEM和TEM电镜观察结果表明 ,该工艺可以获得增强颗粒分布均匀、基体组织致密、界面结合良好且无界面反应的复合材料型材。分析了半固态挤压后复合材料的力学性能 ,结果表明 :与基体合金相比 ,复合材料的弹性模量、屈服强度、抗拉强度均有很大提高 ;与其它工艺生产的该复合材料相比 ,所制备的复合材料的塑性相对较高。     

基于SPS-热轧法钨颗粒增强铝基复合材料微观组织及力学性能研究

本文采用放电等离子烧结→热轧制方法制备了颗粒含量为1～7%的钨颗粒增强铝基复合材料,研究钨颗粒含量对复合材料的微观组织、机械性能和导电性能的影响。研究结果表明：钨颗粒均匀的分布在基体铝合金当中,W/Al界面之间达到了冶金结合,在界面处存在元素扩散和WAl12金属间化合物的生成。在复合材料中,随着钨颗粒含量的增加,复合材料的致密度和韧性降低而拉伸强度呈现先升高后降低的趋势。其中,1和3 vol.% W/Al复合材料的拉伸强度和断裂韧性分别为192.85 MPa (16.84%) 和315.18 MPa (11.93%)。此外,W/Al复合材料具有良好的电导率,W颗粒的含量对复合材料的影响较小。     

Effects of nano-SiCp content on microstructure and mechanical properties of SiCp/A356 composites assisted with ultrasonic treatment

nano-SiC_p/A356 composites with different nano-SiC_p contents were prepared by squeeze casting after ultrasonic treatment (UT). The effects of SiC_p content on the microstructure and mechanical properties of the nanocomposites were investigated. The results show that with the addition of nano-SiC_p, the microstructure of nanocomposites is obviously refined, the morphology of the α(Al) grains transforms from coarse dendrites to rosette crystals, and long acicular eutectic Si phases are shortened and rounded. The mechanical properties of 0.5%, 1% and 2% (mass fraction) SiC_p/A356 nanocomposites are improved continuously with the increase of nano-SiC_p content. Especially, when the SiC_p content is 2%, the tensile strength, yield strength and elongation are 259 MPa, 144 MPa and 5.3%, which are increased by 19%, 69% and 15%, respectively, compared with those of the matrix alloy. The improvement of strength is attributed to mechanisms of Hall-Petch strengthening and Orowan strengthening.     

Effect of alumina short fiber and air-cooling processing on solidification microstructure and tensile properties of Al2O3/Al-15Si composites

The effect of microstructure variation by addition of alumina short fiber and optimization of tensile properties by air-cooling processing in Al2O3/Al-15Si composites were studied.The results show that in Al-015Si alloy matrix composites with 14% and 30%(volume fraction)fiber,the primary silicon is hardly refined,but the eutectic silicon is effectively refined and granulated.Granulation of some eutectic silicon mainly happens in fiber segregation areas.Refining and granulation of the eutectic silicon are related to the physical constraint arising from the fiber,After the 30%Al2O3/Al-15Si composite was remelted and air-cooled,the number of the eutectic silicon on the surface of the fiber increases,which results in the improvement of fiber/matrix interface and tensile properties for the as-cast composite,Air-cooling processing may be reliable for the optmization of the microstructure and properties of fiber reinforced hypereutectic Al-15Si alloy composites.