Fe2Al5相的一种电子衍射斑点分析

利用透射电子显微镜(TEM)研究了热浸渗铝钢中Fe2Al5相.结果表明,Fe2Al5相的一种电子衍射花样特征与正六边形非常接近.但通过分析,其电子衍射花样并非严格的正六边形.其应属正交晶系.     

碳(石墨)/铝复合材料的高温拉伸强度

本文初步研究了C/LD₂和M40/LD₂复合材料高温拉伸强度。在室温至400℃温度范围内,C/LD₂和M40/LD₂均能保持其室温强度。在500℃时C/LD₂的强度保持率为84.10%。      

Improvement of the tensile strength of Al18B4O33w/Al composite at elevated temperatures by change of interfacial state

In general, it is very difficult to obtain obviously reinforced effect in discontinuously reinforced aluminum matrix composites at the temperature above 400 °C. In the present study, we report an effective method to improve the high-temperature tensile strength of Al₁₈B₄O₃₃w/Al composite by change of interfacial state. The pure aluminum matrix composites reinforced by Al₁₈B₄O₃₃w with different ZnAl₂O₄ coating contents were fabricated by squeeze casting. The results indicate that ZnAl₂O₄ coating of the whiskers can effectively improve the high-temperature tensile strength of Al₁₈B₄O₃₃w/Al composite, although the tensile strength of the composite decreases with increasing the tensile temperature. On the basis of fractograph analysis, the fracture mechanism of the composites at elevated temperatures was investigated.     

Strengthening of Al through addition of Fe and by processing with high-pressure torsion

Iron is a common impurity element in aluminum and is expected to be used in a controlled manner. In this study, high-pressure torsion (HPT) was applied to 10-mm diameter bulk disk-type samples of Al–Fe alloys with different Fe additions: 2 and 4 wt%, and different initial states: as-cast, extruded, and annealed. Intense strain was introduced to the materials by HPT processing at room temperature under a pressure of 6 GPa for up to 75 revolutions. Tensile tests showed that a significant increase in the UTS above 500 MPa occurs with 13 % elongation in the Al–2 % Fe sample processed by HPT from the as-cast state. Microstructural analyses revealed that a close-to nanograined microstructure with a size of 125 nm and dispersion of intermetallic particles below 50 nm was attained, along with a maximum supersaturation of Fe of ~0.67 wt%. The Al–4 % Fe sample reached even higher supersaturation of Fe to ~0.99 % and similar strength but lower elongation due to insufficient fragmentation of coarse intermetallics. It is concluded that the eutectic structures in the cast state are a major contributor to the enhanced strengthening and the retained elongation. The saturated states of the microhardness at equal Fe contents were shown to be similar regardless of the initial state upon sufficient straining by HPT.     

ZnAl2O4涂覆Al18B4O33(w)增强6061Al复合材料界面结构与拉伸性能

使用溶胶2凝胶法在硼酸铝晶须表面制备 ZnAl 2O 4涂层 , 采用挤压铸造法制备了 ZnAl 2O 4涂覆的硼酸铝晶须增强 6061Al 复合材料。研究了 ZnAl 2O 4涂覆对复合材料界面润湿性、 室温拉伸性能以及高温热暴露后界面热稳定性的影响。试验结果表明: 纳米 ZnAl 2O 4涂覆能够明显提高复合材料的界面润湿性 , 从而提高复合材料的室温拉伸性能; 均匀的 ZnAl 2O 4涂覆能有效地阻碍界面反应 , 使复合材料具有良好的热稳定性能。研究了涂覆对复合材料在铸态及高温热暴露后拉伸断裂行为的影响。未涂覆硼酸铝晶须增强的铝基复合材料在拉伸变形过程中晶须以折断为主 , ZnAl 2O 4涂覆硼酸铝晶须增强的铝基复合材料在拉伸变形过程中晶须以拔出为主。     

热循环对碳(石墨)/铝复合材料拉伸强度的影响

研究了四种碳(石墨)/铝复合材料经R.T～450℃温度区间热循环之后拉伸强度的变化。结合扫描电镜的断口分析,对界面结合强度与拉伸强度的关系进行了定性的讨论。      

HP40Nb钢热浸镀Al-Si高温氧化行为及组织研究

为提高高温抗氧化性能,对HP40Nb钢进行了热浸镀Al-10%(质量分数)Si,并进行不同温度扩散处理,研究了不同扩散处理试样在1000℃条件下的高温氧化行为,通过SEM,EDS和XRD分析了经不同扩散处理后的渗层在高温氧化过程中的组织结构变化.结果表明:经800℃/4h扩散处理,渗层由内层(NiAl+ Cr3 Si)...     

A general perspective of Fe–Mn–Al–C steels

During the last years, the scientific and industrial community has focused on the astonishing properties of Fe–Mn–Al–C steels. These high advanced steels allow high-density reductions about ~?18% lighter than conventional steels, high corrosion resistance, high strength (ultimate tensile strength ~?1 Gpa), and at the same time ductility above 60%. The increase in the tensile or yield strength and the ductility at the same time is almost a special feature of this kind of new steels, which makes them so interesting for many applications such as in the automotive, armor, and mining industry. The control of these properties depends on a complex relationship between the chemical composition of the steel, the test temperature, the external loads, and the processing parameters of the steel. This review has been conceived to elucidate these complex relations and gather the most important aspects of Fe–Mn–Al–C steels developed so far.     

颗粒增强Fe3Al基复合材料的制备和性能

用熔铸法制备了ＳｉＣ,Ａｌ２Ｏ３和ＴｉＢ２颗粒增强Ｆｅ－２８Ａｌ－５Ｃｒ基复合材料,研究了材料的微观组织和力学性能,结果表明,Ａａ２Ｏ３在Ｆｅ３Ａｌ中的化学稳定性很好,ＴｉＢ２与基体发生了部分反应,ＳｉＣ与基体的反应严重,复合材料在室温和高温下的力学性能的变化说明,上述颗粒的加入使材料的强度较大幅度的提高,塑性有所下降。     

TiC/Fe-Al原位复合材料制备及其显微结构

本文研究了用废弃的钢和球墨铸铁以及钛铝添加剂为原料,经熔炼和热处理制备TiC/Fe3Al复合材料的工艺过程.用光学显微镜、XRD等方法观察了复合材料的相组成、显微结构(TiC颗粒的大小和形状),进而分析了原料成分、热处理时间和温度对原位反应、TiC颗粒的生成及显微结构的影响规律.     

Al–Cu–Fe coatings manufactured by the flame spraying process

Two-hour milled (activated) Al–20Cu–15Fe (at%) powders were subjected to annealing at 600°C for 1?h. The phase and microstructural evolutions were characterized by X-ray diffractometry and scanning electron microscopy. Al₇Cu₂Fe and Al₆₀Cu₃₀Fe₁₀ phases were formed after annealing. Both annealed and milled powders were consolidated using the flame spraying process. In both cases, FeAl(Cu) was the major phase while some oxides and α-Fe(Al,Cu) were also found. The coating produced from the milled powder was severely cracked and showed higher oxide content. The coating prepared from the annealed powder showed better quality. It was annealed at 600°C for 1?h to investigate the thermal stability of the various phases. All phases persevered after annealing while the Fe₂Al₅ phase was formed as a new phase.     

Fine structures in Fe3Al alloy layer of a new hot dip aluminized steel

The fine structure in the Fe-Al alloy layer of a new hot dip aluminized steel (HDA) was examined by means of X-ray diffractometry (XRD), electron diffraction technique, etc. The test results indicated that the Fe-Al alloy layer of the new aluminized steel mainly composed of Fe₃Al, FeAl and α-Fe (Al) solid solution. There was no brittle phase containing higher aluminum content, such as FeAl₃ (59.18% Al) and Fe2Al7 (62–93% Al). The tiny cracks and embrittlement, formerly caused by these brittle phases in the conventional aluminum-coated steel, were effectively eliminated. There was no microscopic defect (such as tiny cracks, pores or loose layer) in the coating. This is favourable to resist high temperature oxidation and corrosion of the aluminized steel.     

冲击拉伸下Fe3Al力学性能的应变率相关性研究

利用自行研制的旋转盘式杆杆型冲击拉伸试验装置于Ｆｅ３Ａｌ实施了不同应变率的冲击拉伸试验，获得了不同应变率下的完整的应力应变曲线，结果表明在应变率从８０Ｓ＾－１至１２００Ｓ＾－１范围内，Ｆｅ３Ａｌ存在明显的动态韧性现象及应变率强化效应，其屈服应力，破坏应力以及破坏应变都随应变率的提高而增加，用最小二乘法拟合得到其屈服应力，破坏应力以及失稳应变与应变率的关系，并根据Ｂｏｎｄｎｅｒ－Ｐａｒｔｏｎ的理论建     

热浸镀铝球墨铸铁失效机理研究

采用VK-9710型激光共聚焦显微镜对热浸镀铝球墨铸铁试样的三点弯曲失效过程进行原位观察,分析镀层和基体的裂纹萌生和扩展机理。结果表明:对于纯Al浸镀球墨铸铁,在拉应力作用下,铁铝合金镀层率先萌生裂纹,诱导临近基体中铁素体撕裂与石墨球剥离,裂纹近似垂直于拉应力方向并沿着临近石墨球最短途径扩展;压应力导致表面纯Al层剥离和铁铝合金层破碎,镀层失效对球墨铸铁基体基本无影响。对于Al-3.7Si-1.0RE浸镀球墨铸铁,拉应力作用下的失效机理与纯Al浸镀相似;压应力作用下纯Al层和铁铝合金层与基体脱开,表现为铁素体基体失效。     

Al2O3@Y3Al5O12纳米短纤维对铝合金基复合材料的增强作用

采用一种具有芯-壳结构的复合纳米纤维增强铝合金复合材料,可以在提高抗拉强度的同时增加塑性。通过真空热压烧结技术制备了Al₂O₃@Y₃Al₅O₁₂复合纳米短纤维增强2024铝合金复合材料。研究了纤维添加质量分数对复合材料致密度、硬度、抗拉强度及延伸率的影响;并探究了芯-壳结构在复合材料增韧中的作用。结果表明:Al₂O₃@Y₃Al₅O₁₂纳米短纤维具有良好的分散性,在超声分散及机械搅拌混粉后均匀吸附在铝合金颗粒表面,无分层及团聚现象;经热压烧结后,Al₂O₃@Y₃Al₅O₁₂纳米短纤维以短纤维形态均匀分散在铝合金基体内,少量添加Al₂O₃@Y₃Al₅O₁₂纳米短纤维起到了桥联和孔洞填充作用,使复合材料致密度和硬度提高;添加质量分数为1wt%时,抗拉强度和延伸率取得最大值,由铝合金的249.3 MPa、2.9%增加到299.1 MPa、4.3%。Al₂O₃@Y₃Al₅O₁₂纳米短纤维的添加可以细化晶粒,阻碍裂纹扩展,且在拔出/断过程中Al₂O₃@Y₃Al₅O₁₂纳米短纤维芯-壳结构的塑性变形起到了增强增韧作用。      

Fe3Al基金属间化合物涂层的研究进展

Fe3Al金属间化合物具有良好的高温性能,在钢表面制备Fe3Al基金属间化合物涂层能有效提高基体在高温下的抗氧化、耐腐蚀、耐摩擦和抗冲蚀性能,其抗硫化性能甚至优于不锈钢.相比于同等功能的陶瓷涂层,Fe3Al涂层与基体有更好的相容性.综述了Fe3Al基金属间化合物涂层的研究现状,介绍了涂层性能及影响因素,涂层制备的主要工艺方法和技术特点,主要包括热喷涂、堆焊、激光合成等.     

Alignment behavior of primary Al3Fe phase in Al–Fe alloy under a high magnetic field

The influence of a high magnetic field on the alignment behavior of primary Al₃Fe phase in Al–Fe alloy was investigated. It was found that the primary Al₃Fe phase with plate-like morphology was gathered at the bottom of the sample without the high magnetic field. However, they aligned perpendicularly to the magnetic field direction and their homogeneous distribution throughout the sample was achieved when the high magnetic field was imposed. The results of X-ray diffraction (XRD) showed that the paramagnetic Al₃Fe phase was magnetized to align to a preferred direction <543> due to crystal magnetic anisotropy in the high magnetic field up to 12 T.     

Bonding strength of Al/Mg/Al alloy tri-metallic laminates fabricated by hot rolling

One of major drawbacks of magnesium alloy is its low corrosion resistance, which can be improved by using an aluminized coating. In this paper, 7075 Al/Mg-12Gd-3Y-0·5Zr/7075 Al laminated composites were produced by a hot roll bonding method. The rolling temperature was determined based on the flow stresses of Mg-12Gd-3Y-0·5Zr magnesium alloy and 7075 Al alloy at elevated temperature. The bonding strength of the laminate composites and their mechanism were studied. The effects of the reduction ratio (single pass), the rolling temperature, and the subsequent annealing on the bonding strength were also investigated. It was observed that the bonding strength increased rapidly with the reduction ratio and slightly with the rolling temperature. The bonding strength increases with the annealing time until the annealing time reaches 2 h and then decreases. The mechanical bond plays a major role in the bonding strength.     

冷轧对Al_(10)Cu_(25)Co_(20)Fe_(20)Ni_(25)高熵合金组织结构及力学性能的影响

对铸态Al10Cu25Co20Fe20Ni25高熵合金进行冷轧处理后进行室温拉伸测试,并利用X射线衍射仪(XRD)和扫描电镜(SEM)分别对其相结构、微观组织形貌及拉伸断口进行分析。结果表明:经冷轧工艺处理后,Al10Cu25Co20Fe20Ni25高熵合金硬度最大为285HV,较轧制前提高了51.6%;在变形量为40%时,抗拉强度达到最大值,为638MPa,是铸态合金的2.7倍。拉伸断口分析表明,铸态合金的断裂模式为树枝晶沿晶断裂和韧窝型延性断裂,而冷轧态合金主要为韧窝型延性断裂模式。     

原位自生TiC颗粒对Al8.5Fe1.4V1.7Si耐热铝合金的组织及性能的影响

利用原位自生技术向Al8.5Fe1.4V1.7Si耐热铝合金中添加一定数量的TiC颗粒,利用金相、X-射线以及透射电镜等手段,分析了材料的组织结构特点,研究了原位TiC粒子对材料的组织结构的影响规律,并测试了材料的力学性能.研究结果表明:原位TiC粒子可以有效地抑制合金中粗大相的产生,促进球状Al12(Fe,V)3Si相的形成;通过添加原位TiC粒子,可以将材料的力学性能提高10%左右,而材料塑性变化不大.