原位反应合成致密Al2O3p-TiCp/Al复合材料

本文采用高能球磨、原位反应合成及热压技术制备了致密的Al2O3p-TiCp/Al复合材料,并用XRD、SEM以及EDAX等手段分析了复合材料的相组成、显微组织.结果表明:Al-TiO2-C三元体系在热压反应烧结后,可制得致密度较高的Al2O3p-TiCp/Al原位复合材料,其显微组织中Al2O3和TiC颗粒尺寸为1μm左右,分布均匀.高能球磨有利于增强颗粒细化弥散分布和反应进行完全.     

原位反应合成致密Al2O3p-TiCp/Al复合材料

采用高能球磨细化晶粒、原位反应合成及热压技术制备了致密的Al2 O3 p TiCp/Al复合材料 ,并用XRD、SEM、以及EDAX等手段分析了复合材料的相组成、显微组织。结果表明 :Al TiO2 C三元体系在热压反应烧结后 ,可制得致密度较高的Al2 O3p TiCp/Al原位复合材料 ,其显微组织中Al2 O3 和TiC颗粒尺寸为 1μm左右 ,分布均匀。高能球磨有利于增强颗粒细化及弥散分布和反应。     

原位自生Al2O3颗粒增强Al基复合材料的研究

本研究是在Al基材料中加入了Cu3O颗粒,原位反应生成Al2O3颗粒,从而增强Al基材料.研究采用粉末冶金的方法,先冷压成型,再热压,在温度680~C压℃力1MPa时保温10分钟,成功制备了Al2O3/Al基复合材料.研究了Cu2O含量对该复合材料的密度、硬度、抗弯强度等性能的影响,结果表明:Al-8Ni-3Cu-2Cu2O复合材料的综合性能最好,硬度达到78.66HRF,抗弯强度达到254.35MPa.利用扫描电镜观察复合材料的表面形貌(SEM图像),并对试样成分进行分析(BSE图像),发现试样的成分分布比较均匀.通过XRD图谱和热力学分析表明:经热压后,该复合材料新生成物相主要为Al2O3.     

原位自生Mg_2Si/A1-Si复合材料的稀土与锶盐变质研究

研究了稀土与锶盐复合变质及热处理对原位自生Mg2Si/Al-Si复合材料微观组织的影响。结果表明:随冷却速度的加大,SrCl2与RE复合变质剂对Mg2Si/Al-Si凝固组织中初生α-A1与共晶Si相的变质作用均加强,初生α-A1晶粒生成量增多同时形貌发生趋向球状的转变,共晶Si相形貌则发生板片状向短棒状的转变;在冷却速度较低的砂型铸造条件下,Mg2Si/Al-Si材料凝固组织中,三元共晶Si相受变质剂作用不明显,依然呈板片状生长,此时其可作为三元共晶Mg2Si相的异质形核基底,共晶Mg2Si便依附其上生长;热处理可使Mg2Si/Al-Si铸态组织中共晶硅相转变成细小的颗粒状,断网状的共晶Mg2Si转变成细小的棒状甚至颗粒状,优化了材料组织。     

原位自生钛基复合材料的研究进展

原位自生钛基复合材料以其高比强度和高比模量引起了人们的广泛关注,尤其是如何提高其高温性能成为近年来钛基复合材料研究的热点.该文详细综述了原位自生钛基复合材料的各种制备方法、增强体与钛基体的选择、各种增强体的反应体系以及原位自生钛基复合材料的组织结构与力学性能,指出了原位自生钛基复合材料今后的发展方向.     

原位自生金属基复合材料的制备方法

介绍了原位自生金属基复合材料的性能,概述了几种原位制备颗粒增强金属基复合材料(MMCs)的方法:包括自蔓延高温合成法(SHS)、弥散放热法(XD法)、直接反应法(DRS)、混合盐反应法、接触反应法、反应喷射沉积法、反应挤压铸造法、VLS法等.最后指出要达到工业生产应用,还需要解决的一些难题,并指明了今后的研究方向.     

原位自生铝基复合材料γ射线屏蔽性能研究

通过以原位自生铝基复合材料为耐辐照壳体的COMS相机在不同剂量γ射线下的抗噪度实验可知:8％TiB2/2024复合材料的降噪效果接近于同等厚度的铅.同时,该种材料具有高强度低密度等优良力学特性,为新型耐辐射机壳的设计提供了新的可能.)     

Al－TiB_2自生复合材料的燃烧合成研究

研究了Ａｌ－ＴｉＢ＿２体系的燃烧合成过程。用粉末（Ａｌ、Ｔｉ、Ｂ）通过燃烧方法制备（Ａｌ－ＴｉＢ＿２）自生复合材料，采用ＤＴＡ、ＸＲＤ和ＳＥＭ技术对复合材料的形成和结果进行分析研究。得到如下结果：分别用８０％Ａｌ＋２０％（Ｔｉ＋２Ｂ）、９０％Ａｌ＋１０％（Ｔｉ＋２Ｂ）原料粉末，通过燃烧合成可得到Ａｌ－ＴｉＢ＿２，制备过程中产生少量ＴｉＡｌ＿３，Ａｌ基体与ＴｉＢ＿２结合紧密，无明显界面存在。     

原位自生TiB增强Ti-55531合金复合材料组织与力学性能研究

采用真空自耗电弧熔炼及近等温热塑性变形方法制备了原位自生TiB/Ti-55531复合材料。利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)及万能材料试验机等研究了增强相含量对其组织与力学性能的影响规律,并分析其失效断裂机制。结果表明,热处理态TiB/Ti-55531复合材料的组织特征为α相、TiB增强相弥散分布于β基体。随着TiB增强相的引入及含量增加,复合材料的基体晶粒明显细化,沿晶界分布的粗条状α相逐渐球化,抗拉强度、屈服强度、杨氏模量明显增加,延伸率有不同程度降低。2vol%TiB/Ti-55531复合材料的强塑性匹配较好,抗拉强度为1444.2 MPa,屈服强度为1421.4 MPa,杨氏模量为115.5 GPa,延伸率为9.2%。随着TiB增强相的引入及含量增加,拉伸试样断口的韧窝数量减少,深度变浅,断裂机制逐渐从韧性断裂向混合断裂转变。     

原位还原法制备Al/Al2O3复合材料的力学性质及反应动力学

以石英为先驱体,以液态铝为还原剂,在1073～1523 K的温度范围内对原位生成铝/氧化铝复合材料进行了研究,对获得的复合材料的物理和机械性能做了测定,并对材料显微结构进行了观测和分析.在1473K制备的铝/氧化铝复合材料密度为2.95g/cm3,最大弹性模量为130 GPa,最大三点抗弯强度为580 MPa,最大拉伸强度为268 MPa,洛氏硬度为86.产物铝/氧化铝复合材料的形状与作为先驱体的二氧化硅的形状几乎一致.讨论了反应过程的动力学.     

Reduction Behavior of Hematite-Biowaste Composite Pellets at Melting Temperature

The iron and steel industry is one of the prominent industrial sectors in the world since steel is a vital material with a wide range of applications in daily life. The ferrous industries are associated with various issues like extensive greenhouse gas emissions, energy-intensive processes, and heavy reliance on fossil fuels and natural resources. At the same time, concern regarding waste generation and its management is taking up the momentum and calls are being made for recycling and green recovery. The reuse of waste materials in the manufacturing process can make the industries’ circular economy resilient. Thus, the current work is based on the usage of a biowaste, namely, spent coffee grounds for hematite reduction. Composite pellets of hematite and transformed-spent coffee grounds (T-SCGs) are heat-treated at a melting temperature of 1550 °C. The effect of both binary and quaternary basicity on the reduction behavior is also studied. T-SCGs have hydrogen in their molecular structure which enhances the reduction mechanism. Overall, the employment of biowaste for iron recovery will aid in making the industry sector more sustainable.     

Hot Ductility and Compression Deformation Behavior of TRIP980 at Elevated Temperatures

The hot ductility tests of a kind of 980 MPa class Fe-0.31C (wt pct) TRIP steel (TRIP980) with the addition of Ti/V/Nb were conducted on a Gleeble-3500 thermomechanical simulator in the temperatures ranging from 873 K to 1573 K (600 °C to 1300 °C) at a constant strain rate of 0.001 s^?1. It is found that the hot ductility trough ranges from 873 K to 1123 K (600 °C to 850 °C). The recommended straightening temperatures are from 1173 K to 1523 K (900 °C to 1250 °C). The isothermal hot compression deformation behavior was also studied by means of Gleeble-3500 in the temperatures ranging from 1173 K to 1373 K (900 °C to 1100 °C) at strain rates ranging from 0.01 s^?1 to 10 s^?1. The results show that the peak stress decreases with the increasing temperature and the decreasing strain rate. The deformation activation energy of the test steel is 436.7 kJ/mol. The hot deformation equation of the steel has been established, and the processing maps have been developed on the basis of experimental data and the principle of dynamic materials model (DMM). By analyzing the processing maps of strains of 0.5, 0.7, and 0.9, it is found that dynamic recrystallization occurs in the peak power dissipation efficiency domain, which is the optimal area of hot working. Finally, the factors influencing hot ductility and thermal activation energy of the test steel were investigated by means of microscopic analysis. It indicates that the additional microalloying elements play important roles both in the loss of hot ductility and in the enormous increase of deformation activation energy for the TRIP980 steel.     

Hot Deformation Behaviors of Fe–30Mn–3Si–3Al TWIP Steel during Compression at Elevated Temperature and Strain Rate

The hot deformation behavior of twinning‐induced plasticity (TWIP) steel was investigated at 973–1373 K and strain rates of 0.01–20 s^?1 by hot‐compression experiments performed on a Gleeble‐3800 thermo‐simulation test system. Microstructural evolution during recrystallization in the hot deformed TWIP steels was investigated by metallurgical analysis. The hot‐flow behavior can be represented by a Zener–Hollomon parameter in the hyperbolic‐sine equation. The hot‐deformation activation energy is 436.813 kJ mol^?1. Deformation bands are initially generated in the deformed austenitic grains during the dynamic recrystallization (DRX) of TWIP steel. With increasing temperature, the recrystallized grains emerge at the boundary junctions after the disappearance of the deformation bands. Subsequently, they gradually spread along the austenitic boundaries and exhibit a necklace shape. The dynamic recrystallized grains continuously grow until they finally reach equilibrium. The DRX mechanism of TWIP steel is a boundary bulge mechanism. The optimum hot‐working technology parameters (especially for rolling) for the TWIP steel is the deformation temperature range of 1223–1323 K, and strain rate range of 1–10 s^?1.     

富镧混合稀土对莫来石短纤维增强ZL109复合材料高温强度的影响

本文作者在基体合金中加入适量富镧混合稀土和适当提高锰量及铁量,使该复合材料在３００℃时的瞬时强度提高到１６５ＭＰａ,３５０℃时的瞬时强度提高到１１４ＭＰａ,４００℃时的瞬时强度提高到７７ＭＰａ。作者通过对莫来石短纤维增强ＺＬ１０９ 复合材料的高温强度特性及高温下的断裂机理的分析,认为适量加入富镧混合稀土,可以改善基体合金液同纤维之间的润湿状况,生成以纤维为基底长大的金属间化合物,从而改善纤维和基体之间的结合状况     

Effect of Volume Fraction of Particle on Wear Resistance of Al2O3／Steel Composites at Elevated Temperature

Inpreviouswork,heat resistingsteelwithlow carboncontentandhighoxidationresistanceatele vatedtemperaturewastakenasthematrixmaterial. AndAl2O3ceramicparticleswereutilizedasrein forcedphasefortheirgreatstabilityandhighrigidi tyatelevatedtemperature.Inorde…     

Cu-Cr-Zr-Ce合金高温流变应力的研究

利用Gleeble-1500D热模拟试验机对Cu-Cr-Zr-Ce合金在变形温度为600～800℃、应变速率为0.01～5 S-1条件下进行了热压缩试验,测定了其应力-应变曲线,并通过光学显微镜观察了其热压缩过程中的微观组织.结合两者分析了动态回复和再结晶机制.结果表明,动态再结晶是该合金软化的主要机制.     

复合材料Al/Al4C3/Al2O3的组织结构与力学性能

采用机械合金化（ＭＡ）球磨和热压烧结工艺制备了复合材料Ａｌ／Ａｌ４Ｃ３／Ａｌ２Ｏ３，对其组织结构和力学性能进行了研究。结果表明，发育良好的Ａｌ４Ｃ３棒状单晶体和等轴状γＡｌ２Ｏ３均匀分布在铝晶界或晶粒内部，二者体积含量约为６６ｖ％。Ａｌ／Ａｌ４Ｃ３和Ａｌ／Ａｌ２Ｏ３界面洁净，为直接的原子结合，但不存在确定的位向关系。复合材料的室温、高温强度及刚度比粉末冶金纯铝（Ｐ／ＭＡｌ）显著提高。     

喷射成形GH742y高温合金的高温变形特性

喷射成形是利用快速凝固方法制备高性能金属材料的先进的,低成本的净成形技术.本文研究了变形温度和应变速率对喷射成形GH742y高温合金热工艺塑性的影响.研究结果表明,喷射成形GH742y合金具有良好的热变形能力.不过,变形温度和应变速率对喷射成形GH742y合金的变形抗力也有较大的影响.     

致密烧结Ti/Al2O3复合材料

利用放电等离子烧结技术(SPS)制备出相对密度、断裂韧性、弯曲强度分别为99.74%、19.73±0.4MPa·m1/2、1002±12MPa的40vol%Ti/Al2O3复合材料。SEM对复合材料表面形貌观察发现,Ti、Al2O3两相分布均匀,表面无明显气孔存在;断口的SEM和EDS表明,复合材料已形成网络导电结构;复合材料的HREM微观结构分析表明,Al2O3三角晶界处无其它杂质的偏聚,小颗粒的金属Ti富集在Al2O3的三角晶界结合处,界面结合紧密。     

Study of Structural and Mechanical Properties of Al/Nano-Al2O3 Metal Matrix Nanocomposite Fabricated by Powder Metallurgy Method

In this work, the (1???x) Al–xAl₂O₃ (x?=?0, 1, 2, 3, and 4 wt%) of metal matrix nanocomposites (MMNCs) has been manufactured using the powder metallurgy technique. Aluminium metal powder (Al) was used as the matrix material, and alumina nanoparticles (Al₂O₃) synthesized by the sol–gel method were used as the reinforcing material to produce the MMNCs. Two phases of Al₂O₃ have been identified, i.e. the α-phase (rhombohedral structure) and the δ-phase (orthorhombic structure) by X-ray diffraction patterns (XRD) of synthesized Al₂O₃ nanoparticles with an average crystallite size of 31.33 nm. The average particle size of the Al₂O₃ nanoparticle is obtained as 39.6 nm. The XRD patterns of the Al–Al₂O₃ nanocomposites contain the Al and Al₂O₃ peaks that confirm the development of the MMNC without any solid-state reaction during the manufacturing process. FESEM micrographs show an almost uniform distribution of Al₂O₃ particles in the Al metal matrix. The reinforcement of the Al₂O₃ nanoparticles in the Al metal matrix has shown an improvement in hardness by increasing the wt% of Al₂O₃ in Al matrix, and a maximum 24.8% improvement in hardness is observed for 4 wt% Al₂O₃ sample. An increase in wear rate is observed with the increasing wt% of Al₂O₃ in the Al metal matrix in Al–Al₂O₃ nanocomposite. The addition of Al₂O₃ nanoparticles in the Al matrix has resulted in improved corrosion performance of the samples with a maximum corrosion resistance efficiency of 85.6% for 4 wt% Al₂O₃ in Al metal matrix.