Compressive response and microstructural evolution of in-situ TiB_(2)particle-reinforced 7075 aluminum matrix composite

The hot forming behavior,failure mechanism,and microstructure evolution of in-situ TiB_(2)particle-reinforced 7075 aluminum matrix composite were investigated by isothermal compression test under different deformation conditions of deformation temperatures of 300−450℃ and strain rates of 0.001^(−1)s^(−1).The results demonstrate that the failure behavior of the composite exhibits both particle fracture and interface debonding at low temperature and high strain rate,and dimple rupture of the matrix at high temperature and low strain rate.Full dynamic recrystallization,which improves the composite formability,occurs under conditions of high temperature(450℃)and low strain rate(0.001 s^(−1));the grain size of the matrix after hot compression was significantly smaller than that of traditional 7075Al and ex-situ particle reinforced 7075Al matrix composite.Based on the flow stress curves,a constitutive model describing the relationship of the flow stress,true strain,strain rate and temperature was proposed.Furthermore,the processing maps based on both the dynamic material modeling(DMM)and modified DMM(MDMM)were established to analyze flow instability domain of the composite and optimize hot forming processing parameters.The optimum processing domain was determined at temperatures of 425−450℃ and strain rates of 0.001−0.01 s^(−1),in which the fine grain microstructure can be gained and particle crack and interface debonding can be avoided.

TiB2／Al复合材料制备工艺的研究进展

TiB_2/Al复合材料是一种很有潜力的复合材料,在耐磨、航天航空等领域有着广阔的应用前景。目前TiB_2/Al复合材料的制备工艺方法主要为原位自生法,如自蔓延高温合成、原位反应生成法、接触反应法和机械合金化法等,而粉末冶金法、喷射沉积法以及挤压铸造法等也逐渐被用于制备TiB_2/Al复合材料。主要综述了目前国内外TiB_2/Al复合材料制备工艺的研究进展,并对不同工艺的制备过程及利用该工艺所制备的TiB_2/Al复合材料的情况进行了详细论述,指出了各种制备工艺的优缺点,展望了其研究趋势。

超声外场对原位TiB2/2A14铝基复合材料的摩擦磨损性能的影响

采用超声外场-原位混合盐反应法制备3%TiB 2/2A14(体积分数)铝基复合材料,在往复式摩擦磨损试验机上进行4种不同载荷(20,30,40,50N)的磨损实验,研究不同超声处理工艺制备的复合材料的耐磨性和摩擦行为。使用显微硬度计测量基体和复合材料的显微硬度。采用X射线衍射仪、扫描电子显微镜对测试样品进行物相成分鉴定、显微组织和表面磨损形貌观察,并研究其磨损机理。结果表明:超声能够有效打散颗粒团聚,改善颗粒分布状态,强化颗粒与基体的界面结合强度,因此经过超声处理的复合材料的耐磨性和显微硬度明显优于合金基体。经120s超声处理获得的复合材料,其硬度约为基体合金的2倍。在50N载荷的作用下,其磨损率约为基体合金的57.43%。在干摩擦条件下,基体主要表现为黏着磨损,复合材料表现为黏着磨损+磨粒磨损的混合型磨损,耐磨性能更佳。

Effect of baking processes on properties of TiB_2/C composite cathode material

Pitch and TiB2/C green composite cathode material were respectively analyzed with simultaneous DSC-TGA, and effects of three baking processes of TiB2/C composite cathode material, i.e. K25, K5 and M5, on properties of TiB2/C composite cathode material were investigated. The results show that thermogravimetrie behavior of pitch and TiB2/C green composite cathode is similar, and appears the largest mass loss rate in the temperature range from 200 to 600 ℃. The bulk density variation of sample K5 before and after baking is the largest （11.9%）, that of sample K25 is the second, and that of sample M5 is the smallest （6.7%）. The crushing strength of sample M5 is the biggest （51.2 MPa）, that of sample K2.5 is the next, and that of sample K5 is the smallest （32.8 MPa）. But, the orders of the electrical resistivity and electrolysis expansion of samples are just opposite with the order of crushing strength. The heating rate has a great impact on the microstructure of sample. The faster the heating rate is, the bigger the pore size and porosity of sample are. Compared with the heating rate between 200 and 600℃ of samples K25 and K5, that of sample M5 is slower and suitable for baking process of TiB2/C composite cathode material.

Property Characteristics of a TiB_(2P)/Al Composite Fabricated by Squeeze Casting Technology

TiB2P/Al composite was successfully fabricated by squeeze casting technology.Its mechanical and tribological properties were evaluated .The elimination of Ti-Al intermetallic compound was confirmed by X-ray diffraction （XRD）studies.At 45% volume fraction ,the bending strength at ambient temperature was 934 MPa.And the fracture modes included ductile failure of Al matrix and brittle fracture of TiB2 pqrticles.In dry sliding wear mode ,severe plastic deformation and adhesive wear were found on te worn surfaces of the SiCP/Al composite .But no obvious characteristics of adhesion or abrasion wear were observed on that of the TiB2P/Al composites .At the stedady stage ,the friction coefficient of the SiCP/Al composite was about 0.6 .While that of TiB2P/Al composite was only only about 0.16-0.17.

Evaluation of Wear and Corrosion Properties of AA6061/TiB₂Composites Produced by FSP Technique

Aluminum alloys are used frequently in aerospace and ship building industry. Due to poor wear and corrosion resistance, conventional aluminum alloys are replaced by metal matrix composites (MMC). Aluminum alloy matrix reinforced with ceramic particles (TiB2) has importance in industry where components slide each other. The main task is to produce MMCs with low cost effective way to meet the requirement. In this study, an attempt is made to produce AA6061/TiB2 MMCs with different volume fractions of ceramic particles using friction stir processing technique. The dry sliding wear behavior of composites was investigated using pin on disc method. The lowest wear resistance has obtained for 8% composite. The corrosion of composites was analyzed by salt spray method. It was found that wear and corrosion resistance was increased with increase of reinforcement which was higher for 8% composite.

CR法生成TiB_2/Al复合材料制备工艺研究

在实验的基础上 ,分析 CR法生成 Ti B2 /Al复合材料制备工艺的 5个关键问题 ,得出相应的解决方法 ,制备出了颗粒分布均匀、组织致密、性能较理想的 Ti B2 /Al复合材料 。

原位TiB_2/Al复合材料形核机制

阐述了原位合成制备TiB2 颗粒增强铝基复合材料自生相的形核机制以及转变动力学 ,从热力学和动力学的角度来分析TiB2 的形成机制 ,依据扩散原理讨论TiB2 转变动力学。

Ti,B 化合物制取颗粒增强 TiB_2/Al 复合材料

用熔炼法制备ＴｉＢ２／Ａｌ复合材料．通过添加Ｔｉ，Ｂ化合物，在纯铝基体中原位生成ＴｉＢ２颗粒，基体得以增强．就ＴｉＢ２的体积分数对复合材料机械性能和显微组织的影响进行了研究，并对两种Ｔｉ，Ｂ化合物（Ⅰ，Ⅱ号）的增强效果进行了比较．结果表明，ＴｉＢ２／Ａｌ复合材料的机械性能明显优于铝基体．与Ⅰ号Ｔｉ，Ｂ化合物相比，Ⅱ号Ｔｉ，Ｂ化合物能更有效地提高复合材料的强度和硬度．ＴｉＢ２／Ａｌ复合材料的拉伸强度和硬度随Ｔｉ，Ｂ化合物加入量增多而提高，而延伸率降低．含２．０％（体积分数）ＴｉＢ２的复合材料其热轧退火态的拉伸强度和铸态布氏硬度分别为１５８ＭＰａ和３８８ＭＰａ，与纯铝基体相比，拉伸强度和硬度分别提高了１１１％和５１％．

原位合成铝基复合材料凝固组织中TiB_2粒子的特征

分析了原位合成制备的ＴｉＢ２ 粒子强化铝基复合材料不同凝固组织中ＴｉＢ２ 粒子的分布规律和形貌特征。研究结果表明， ＴｉＢ２ 在该复合材料中细化晶粒的作用较弱， 但有明显的聚集倾向， 其聚集程度与熔炼方式和加热温度有关； 经半固液成型处理的组织中ＴｉＢ２ 的分布特征未改善； 六边形和长条形ＴｉＢ２ 可以是同一形态的粒子在空间不同方位的表现， 六边形ＴｉＢ２ 的侧面为｛１２１０｝ 面； 测定了ＴｉＢ２粒子的尺寸分布。

Effect of Trace Addition of Ceramic on Microstructure Development and Mechanical Properties of Selective Laser Melted AlSi10Mg Alloy

Selective laser melting(SLM)is an emerging additive manufacturing technology for fabricating aluminum alloys and aluminum matrix composites.Nevertheless,it remains unclear how to improve the properties of laser manufactured aluminum alloy by adding ceramic reinforcing particles.Here the effect of trace addition of TiB2 ceramic(1%weight fraction)on microstructural and mechanical properties of SLM-produced AlSi10Mg composite parts was investigated.The densification level increased with increasing laser power and decreasing scan speed.A near fully dense composite part(99.37%)with smooth surface morphology and elevated inter-layer bonding was successfully obtained.A decrease of lattice plane distance was identified by X-ray diffraction with the laser scan speed decreased,which implied that the crystal lattices were distorted due to the dissolution of Si and TiB2 particles.A homogeneous composite microstructure with the distribution of surface-smoothened TiB2 particles was present,and a small amount of Si particles precipitated at the interface between reinforcing particles and matrix.In contrast to the AlSi10Mg alloy,the composites showed a stabilized microhardness distribution.A higher ultimate tensile strength of 380.0 MPa,yield strength of 250.4 MPa and elongation of 3.43%were obtained even with a trace amount of ceramic addition.The improvement of tensile properties can be attributed to multiple mechanisms including solid solution strengthening,load-bearing strengthening and dispersion strengthening.This research provides a theoretical basis for ceramic reinforced aluminum matrix composites by additive manufacturing.

原位TiB_2颗粒增强铝基复合材料形核机制及转变动力学

阐述原位合成制备TiB2 颗粒增强铝基复合材料自生相的形核机制以及转变动力学 ,从热力学和动力学的一般角度来分析TiB2 的形成机制 ,并讨论TiB2

(TiB_2+TiAl_3)/AlSi_6Cu_4复合材料的研究

利用K2 TiF6 +KBF4混合盐和AlSi6 Cu4熔体反应可以制备TiB2 +TiAl3颗粒增强AlSi6 Cu4基复合材料。通过XRD和SEM等仪器对复合材料的凝固组织和力学性能进行了研究 ,随K2 TiF6 和KBF4混合盐加入量的增加 ,原位反应生成的颗粒尺寸减小 ,分布更均匀 ;所得到的AlSi6 Cu4复合材料的强度比AlSi6 Cu4基体明显提高。

LSM法制备TiB_2/Al-7Si复合材料的研究

研究了ＬＳＭ 法制备 ＴｉＢ２ 粒子增强ＡｌＳｉ７ 复合材料的物相组成；考察了ＴｉＢ２ 粒子对热处理组织与性能的影响。研究结果表明，按Ｋ２ＴｉＦ６ ＋ ２ＫＢＦ４＝ ＴｉＢ２ ＋ ４ＫＦ＋ ５Ｆ２ 反应式计算，在ｗ （ＴｉＢ２）为５％ 时，在复合材料中可以生成稳定且均匀分布的ＴｉＢ２ 粒子，未发现ＴｉＡｌ３ 等相。材料的杨氏模量由７２．３ ＧＰａ 提高至９６．８ ＧＰａ。ＴｉＢ２

Sc掺杂TiB_(2)/6061复合材料热变形行为及热加工图

采用Gleeble-3800热模拟试验机对0.2%Sc-2%TiB_(2)/6061复合材料进行热压缩实验,研究了该材料在变形温度为623~773 K、应变速率为0.001~1 s-1条件下的热变形行为,基于应力应变曲线,构建了材料的本构方程及热加工图。结果表明:0.2%Sc-2%TiB_(2)/6061复合材料的流变应力随变形温度的升高和应变速率的降低而降低,材料的热变形激活能为227.751 kJ/mol;在热压缩过程中,失稳区主要出现在高应变速率区域(663~773 K,0.132~1 s-1)及低温区域(623~655 K,0.001~0.040 s-1),最优的热加工区域为变形温度703~773 K、应变速率0.017~0.107 s-1。热变形过程中该材料的软化机制主要为动态回复。

激光增材制造用氧化石墨烯铝基复合粉材的制备与研究

为了降低激光增材制造用铝合金粉材的反射率,采用氧化石墨烯作为增强相,用优化的低温真空湿法球磨工艺的分散方法制备了氧化石墨烯质量分数为0.1%的可用于激光增材制造的铝基复合粉材。结果表明:复合粉材的球形度良好,氧化石墨烯均匀包裹在铝合金粉材表面;复合粉材的激光反射率与纯铝合金粉材相比从58.1%降低到34.5%,更有利于激光增材制造。