复合强化Al_3Ti·AlN/ZL101原位复合材料研究

用 OM及 TEM对 Al3Ti· Al N/ZL 10 1及 Al3Ti/ZL 10 1原位复合材料的微观结构进行了研究 ,并测试了试验材料的力学性能。通过综合分析微观结构对力学性能的影响 ,探讨了原位复合材料的增强机制。研究结果表明 :原位复合材料中由于 0 .5μm左右增强相的存在 ,使基体及共晶硅的晶粒明显细化 ;增强相均匀弥散地分布于α- Al晶粒内部 ,对α- Al有强烈的细化作用 ;复合增强体强化的原位复合材料 Al3Ti· Al N/ZL 10 1比单一增强体强化的原位复合材料Al3Ti/ZL 10 1及基体材料 ZL 10 1有更好的力学性能。细晶强化和弥散强化是本文所述的原位复合材料的主要强化机制     

原位生成AlN-Al3Ti复合增强铝基复合材料研究

研究了AlN-Al3Ti／ZL101原位复合材料的制备工艺，采用OM，SEM及TEM对该材料的微观结构进行了研究，用MTS800力性试验机测试了材料的力学性能。研究表明：在AlN-Al3Ti／ZL101原位复合材料中，尺寸约为0．5tam的Al3Ti增强相均匀弥散分布于α-Al晶粒内部，尺寸为30nm的AlN增强相弥散分布于共晶体内部。增强体使α-Al和共晶体明显细化，起到强化作用。AlN-Al3Ti／ZL101原位复合材料中第二相在Al3Ti与α-Al之间存在共格对应关系。AlN相作为共晶硅的异质晶核使共晶Si显著细化。经热处理后，AlN-Al3Ti／ZLl01复合材料的室温拉伸强度达到369MPa，较基体材料有显著提高。     

铸造ZL101A／SiCp复合材料的研究

采用真空搅拌复合工艺制备了铸造ZL101A／SiC复合材料,研究了变质和细化处理对复合材料组织的影响。结果表明：变质和细化处理铸造 ZL101A／SiC复合材料制备工艺的重要处理措施,可明显改善复合材料的组织。利用透射电镜对AL／SiC界面特征及界面反应进行分析,同时对该复合材料的铸造性能（熔体合金流动性能、线收缩、体收缩和热裂倾向）以及力学和物理性能进行了测试。     

AlN-Al3Ti/ZL101原位复合材料力学性能研究

利用原位反应合成技术制备了AlN Al3 Ti/ZL10 1复合材料 ,分析了复合材料增强相Al3 Ti和AlN的微观组织 ,检测了该复合材料的常规力学性能 ,探讨了原位复合材料的增强和增韧机理。结果表明 :(1)无论是在铸态还是在热处理状态下 ,复合材料的强度和硬度都较基体ZL10 1基体材料的高 ;(2 )AlN Al3 Ti/ZL10 1原位复合材料增强增韧的主要原因是晶粒细化、增强相均匀分布及增强相与基体的协同变形能力强。     

原位自生TiAl3增强Al基复合材料的组织结构及形成机理研究

采用冷喷涂技术沉积Ti-80Al（wt.%）复合涂层,通过热处理获得了原位自生TiAl3金属间化合物颗粒增强Al基复合材料涂层。采用SEM、EDS和XRD等分析了冷喷涂Ti/Al复合涂层在不同热处理温度下的组织结构演变规律及Ti、Al粒子间原位扩散反应过程,并对TiAl3金属间化合物的形成机理进行了探讨。结果表明,冷喷涂Ti/Al复合涂层组织致密,其相结构与喷涂粉末完全相同,450℃热处理后涂层局部区域发生Ti、Al间的固态扩散反应,并在Ti、Al粒子界面原位形成TiAl3金属间化合物,随着热处理温度升高,TiAl3金属间化合物的含量显著增加,600℃热处理后,Ti/Al复合涂层中的Ti粒子全部转变为TiAl3金属间化合物,获得原位自生TiAl3颗粒增强的Al基复合材料.     

原位合成(Al_2O_3+Al_3Ti)_P/Al复合材料的制备研究

通过对Al-TiO_2-SiO_2体系混合粉末固-液原位合成制备出了(Al_2O_3+Al_3Ti)_P/Al复合材料.利用X射线衍射仪、扫描电镜等方法观察分析了其物相和显微组织形貌.结果表明:原位反应制备的(Al_2O_3+Al_3Ti)_P/Al复合材料,金属间化合物增强相Al_3Ti均匀分布于基体,陶瓷相Al_2O_3颗粒非常细小,弥散分布于基体中,使材料的硬度等性能得到提高.     

机械合金化制备Ti(Al,C)复合粉末组织结构研究

目的通过原位合成技术获得Ti(Al,C)复合粉末。方法在不同球磨时间条件下,采用机械合金化方法制备Ti(Al,C)复合粉末,其中Ti粉和Al粉的摩尔比为1:1。采用扫描电子显微镜(SEM)以及X-射线衍射仪(XRD)分析球磨后粉末的显微组织结构及物相,研究不同球磨时间对制备Ti(Al,C)复合粉末物相演变、组织结构及粒子间界面结合状态的影响。结果在球磨过程中,球磨时间越长,粉体的粒径越小,当球磨时间增长到一定程度时,延展性好的Al粉颗粒发生扁平化且其表面积不断增大,使得碎化后的Ti粉颗粒不断嵌入至Al粉颗粒中,最终形成Ti(Al)固溶体。同时根据XRD分析发现,随着球磨时间的延长,Ti(Al,C)复合粉末中的Al峰逐渐减小,说明Al不断固溶到Ti中,形成了一定量的Ti(Al)固溶体。结论通过机械球磨技术在球磨一定时间后可原位合成Ti(Al)固溶体,这说明随着Ti与Al之间的相互扩散,有利于形成Ti(Al)固溶体。     

Zn-Al-Li系和Zn-Al系钎料对SiC_p/ZL101铝基复合材料的润湿性

为表征降熔元素Zn在铝基复合材料钎焊中的扩散行为及其对去膜效果的影响,并改善Zn基钎料的润湿性(添加活性元素Li),用坐滴法在520℃、10~30 min、5 L/min流动Ar保护条件下测试纯Zn、Zn-5Al二元共晶、自制Zn-6Al-1Li三元共晶、自制Zn-21Al-3Li三元包共晶共4种钎料对SiCp/ZL101铝基复合材料的润湿性。结果表明:对于无Li的Zn基钎料,随保温时间的延长,Zn仅在局部范围可沿晶界扩散入Al基体,出现晶界液化甚至溶蚀,但难以出现晶粒液化,钎料/母材界面间隙依然难以消除;对于含Li活性钎料,Li的适度添加(约3%,质量分数)使得Zn的渗入在整个界面趋于均匀分布,消除了局部溶蚀与界面空隙,对润湿性有良好改善效果;Zn的渗入引起大量尺寸约为10μm的(Si)块在界面析出。     

硅酸铝短纤维铝基复合材料耐磨性研究

本文研究了以硅酸铝短纤维作增强体，工业纯铝L00，铸造铝合金ZL101为基体的复合材料耐磨性。并与以颗粒状Al_2O_3为增强体进行对比。结果表明：硅酸铝纤维／ZL101复合材料的耐磨性为ZL101的321倍。在相同摩擦条件下，基体相同的铝基复合材料，以硅酸铝短纤维作增强体较以颗粒Al_2O_3为增强体有着更高的耐磨性。应用摩擦理论推导了磨损方程■与实测吻合。     

原位合成Al_3Ti颗粒增强铝基复合涂层(英文)

以直径200μm、纯度99.5%的钛丝丝网为反应源,通过熔渗-原位反应法制备一种Al3Ti金属间化合物颗粒增强铝基表面复合涂层。差热分析结果表明,在890°C下,Ti丝和Al熔体间发生反应。采用XRD、SEM以及显微硬度和磨损测试对所得到的复合涂层进行表征。结果表明:当保温时间为20min时,钛丝反应完全,原位合成为块状和条状的Al3Ti颗粒;颗粒的显微硬度大约为基体显微硬度的4.5倍;在载荷10N的干滑动磨损条件下,与没有增强的Al基体相比较,保温20min所制备的复合涂层表现出较好的耐磨性,其磨损机制为粘着磨损和磨粒磨损共存。     

双步球磨与放电等离子烧结制备细晶TiAl合金

采用双步球磨法和放电等离子烧结(SPS)技术制备细晶Ti-47Al(at%)合金,利用扫描电子显微镜(SEM)、X射线衍射(XRD)仪以及透射电子显微镜(TEM)等分析测试手段对球磨后的粉末形貌结构、相组成以及烧结块体的显微组织结构进行观察和分析。结果表明:双步球磨粉末的颗粒形状较规则,其颗粒尺寸在20~40μm之间,内部结构均匀,主要由TiAl和Ti3Al相组成。放电等离子烧结后的块体主要由主相TiAl和少量的Ti3Al相及Ti2Al相组成,随着烧结温度的升高,Ti3Al相含量有所增加。当烧结温度为1000℃时,烧结块体获得的主要是等轴晶组织,等轴晶粒尺寸大多数在100~250nm之间。当烧结温度为1100℃时,烧结块体致密、无孔洞,等轴晶粒有明显长大的现象,显微组织主要由等轴状的TiAl相和片层状的Ti3Al相组成。     

T6热处理对Al+SiC预制颗粒增强ZL101/ZL101-Mg基复合材料组织和力学性能影响的研究

通过半固态搅拌铸造的方法制备了Al+SiC预制颗粒增强ZL101基及ZL101-Mg基复合材料,研究了T6热处理对该复合材料微观组织及力学性能的影响。结果表明,T6热处理对Al+SiC预制颗粒增强ZL101基复合材料和Al+SiC预制颗粒增强ZL101+Mg基复合材料中SiC颗粒的分布没有明显影响。但T6热处理使Al+SiC预制颗粒增强ZL101复合材料中共晶硅细化,Al+SiC预制颗粒增强ZL101+Mg复合材料中共晶硅长大变粗。T6热处理对Al+SiC预制颗粒增强ZL101复合材料抗拉强度的平均提升率达到了54.44%,对其伸长率的平均提升率为5.47%。对Al+SiC预制颗粒增强ZL101+Mg复合材料抗拉强度的平均提升率为13.52%,对其伸长率的平均提升率为31.5%。     

PARTICLES ANALYSIS OF Al_2O_3 PARTICLE REINFORCED ZL202 MATRIX COMPOSITES PREPARED BY IN-SITU REACTION

ZL202 matrix composite reinforced by Al2O3 particles was prepared by combining in-situ reaction and casting techniques. Particles' size in the composites was from 1 to 5 microns in diameter. X-ray diffraction analysis verified that the reinforcing particleswere δ-Al2O3 which belong to γ-Al2O3 series. The wetting angle between matrix andreinforcement was less than 90°. Energy spectrum analysis indicated that the reactionin bell cover pressing process took place not so completely as in flouring stir process. When the reaction was finished, the matrix was still ZL202 alloy in both.processes.     

熔铸法制备原位内生Al3Tip/AZ91D复合材料

采用熔铸法制备了Al3Tip体积分数分别为4%和8%的AZ91D复合材料,研究了其显微组织和物相,测试了其致密度、硬度及磨损性能。结果表明,复合材料组织致密,原位内生的Al3Ti颗粒尺寸细小,呈球形且在基体中分布较均匀,与基体结合紧密;随Al3Ti体积分数的增加复合材料的致密度降低,硬度升高,但其耐磨性反而有所降低。与基体AZ91D合金相比,Al3Tip/AZ91D基复合材料的硬度和耐磨性均得到明显提高。     

Effect of pouring temperature on semi-solid slurry of ZL101 alloy prepared by slightly electromagnetic stirring

The semi-solid slurry of ZL101 alloy is prepared by a combination technology of low superheat poudng and slightly electromagnetic stirring. The effects of pouring temperature on the slurry prepared by the technology are investigated. The results indicate that it is feasible to prepare the slurry with globular primary phases by low superheat pouring and slightly electromagnetic stirring, and that the pouring temperature has an important effect on the morphology and the size of primary α-Al in ZL101 alloy. By applying suitable slightly electromagnetic stirring combining with relatively increased pouring temperature, i.e., in a practical way to apply low superheat pouring technology, is capable of obtaining appropriate semi-solid slurry of ZL101 alloy with globular shape of primary phase. Compared with the samples made by low superheat pouring only without stirring, the samples prepared by applying both slightly electromagnetic stirring and low superheat pouring can enable to achieve the same grain size and morphology of the primary phase with that of pouring at 15-35℃ higher.     

TiAl_3对TiC粒子在铝基体中分布及α(Al)晶粒形核的影响

研究TiC和TiAl_3细化工业纯铝时TiAl_3的存在对TiC在铝基体中分布及α(Al)晶粒形核的影响,分析Al-Ti-C晶粒细化机制.结果表明:TiC单独作为工业纯铝的晶粒细化剂时,大量TiC被α(Al)晶粒推向树枝晶的晶界处,从而限制了TiC的异质形核作用;当TiC和TiAl_3共同作为晶粒细化剂时,在α(Al)晶粒内部出现了大量TiC粒子,大量的TiC粒子成为了α(Al)的结晶核心,并且在TiC颗粒和铝基体的界面处存在"富Ti过渡区";TiAl_3在铝熔体中分解释放出Ti原子并向TiC粒子周围偏聚,形成的"TiC/铝熔体界面富Ti过渡区" 改善了TiC与α(Al)的结构适应性,降低了TiC粒子的表面张力,促进了TiC粒子在铝熔体中的均匀分布,提高了其形核能力.     

原位TiC颗粒含量对近液相线铸造7075铝合金二次加热组织的影响

采用原位反应近液相线铸造法制备具有不同原位TiC颗粒含量的TiC_p/7075铝基复合材料,在7075铝合金固-液两相区间(477～635 ℃)的580和600 ℃进行二次加热并保温20 min,水淬固定其半固态组织,应用Image Pro Plus软件测量平均晶粒尺寸及形状因子,研究原位TiC颗粒含量对该合金二次加热组织的影响.结果表明:当原位TiC颗粒质量分数为0～4.4%时,随着原位TiC颗粒质量分数增加,合金铸态组织直接转变为等轴晶组织,且在二次加热过程中,原位TiC颗粒对晶粒的长大行为具有明显的抑制作用;在相同的二次加热条件下,4.4%TiC_p/7075铝基复合材料的平均晶粒尺寸比7075基体合金的减少30～40 μm,更加适合于半固态触变成形.     

Effects of in-situ ZrB2 particle on grain refinement of ZrB2/AZ91D magnesium matrix composite

In-situ ZrB2/AZ91D magnesium matrix composite was successfully synthesized with Al/K2ZrF6+NH4BF4 by means of Direct Melt Reaction.The fabricated ZrB2/AZ91D magnesium matrix composite through direct melt mixing method was investigated.Results from X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDS) confirmed the existence of ZrB2 particles in the AZ91D alloy,and most ZrB2 particles were in the size range of just several microns,some even to 100 nm.The cast specimens were studied through corrosion testing and heat treatment.The average grain size of AZ91D decreased markedly from about 250μm to 50μm.In addition,the shape and size of the β-Mg17Al12 phase as well as the morphologies of primary α-Mg in the magnesium matrix composite were greatly changed.The network structure of the β-Mg17Al12 phase was broken into small blocks and the size of α-Mg decreased significantly.     

Strength and fracture of two hot-rolled Ti–Al–Si–Nb dual phase alloys based on Ti3Al

Ti–Al–Si–Nb dual phase alloys are mainly composed of α₂-Ti₃Al matrix and Ti₅Si₃ silicide phases. In this paper, two alloys (402 and 405) whose Si contents are 2 and 5 at% respectively were arc melted and hot-rolled into sheets with different amounts of deformation. The silicide phase (Ti,Nb)₅(Si,Al)₃ was broken up into small pieces and redistributed in the α₂ matrix during the hot-rolling. Improved strength and ductility of the two alloys were observed after hot-rolling, which can be attributed to both the finely distributed reinforcement silicide phase and refinement of the matrix grain size. The mechanical properties of the two alloys are dependent on their volume fractions of the silicide phase: the strength of alloy 405 is higher than that of alloy 402, while alloy 402 is more ductile than alloy 405. The brittle–ductile transition temperature of the two dual phase alloys is between 600 and 800°C. The surface slip on the dual phase alloys was also observed. Obvious separation between the (Ti,Nb)₅(Si,Al)₃ particles and the α₂ matrix is found on the fracture surfaces obtained at high temperature, showing dimple-like morphology.     

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.