ZM5镁合金合金化阻燃的研究

研究合金元素Ca、富Ce混合稀土的加入对ZM5及ZM5-Li镁合金阻燃性能的影响.燃点测试结果表明,Ca和混合稀土的加入都能明显提高ZM5镁合金的燃点温度.当复合加入1.0%RE和0.8?后,镁合金表面形成致密氧化膜,舍金的起燃温度达到785℃,提高了240℃左右,可以实现无保护条件下的熔炼.然而添加微量Li的ZM5镁合金要达到同样的阻燃效果.添加的Ca量须大于1.5%.     

轻质化MA/ODS镍基高温合金高温氧化行为

采用机械合金化(MA)和真空烧结工艺制备了Y2O3质量分数为2%～20%的氧化物弥散强化(ODS)镍基高温合金,在1 000℃空气中对合金试样进行100h的静态氧化实验,研究了Y2O3含量对合金高温氧化性能的影响与作用机制.结果表明:适量稀土氧化物Y2O3的加入(质量分数≤5%)可促进完整Cr2O3氧化膜的形成,提高氧化膜与合金基体的附着力,改善氧化膜的抗剥落性,减缓合金在1 000℃的氧化速度,从而有效提高合金的抗高温氧化性能.但过量添加则会使其抗氧化性能迅速下降.     

微晶化处理对Fe-Cr合金氧化性能的影响

为提高Fe-Cr合金的抗高温抗氧化性能,采用电火花沉积技术对不同Cr含量的Fe-Cr合金表面进行微晶化处理,研究了铸态和微晶化合金在900℃空气中的抗高温氧化行为。氧化动力学曲线、物相分析、表面和截面形貌表明,当Cr含量较低时,微晶化处理提高了Cr的扩散速度,但不足以生成连续的氧化膜,氧化性能变差;当Cr含量较高时,微晶化处理降低了形成保护性氧化膜的临界含量,微晶化处理的Fe-9Cr和Fe-13Cr合金抗氧化性能明显提高。微晶化处理Fe-13Cr合金的抗高温氧化性能最好,这是由于微晶化处理后13%(质量分数)的Cr可以形成连续致密的保护性氧化膜。因此,微晶化处理是提高材料抗高温氧化性能的有效方法,可应用于高温氧化领域。     

两种沥青路面阻燃剂的阻燃效果研究

研究了氢氧化物阻燃剂和有机磷系阻燃剂对沥青的阻燃效果。采用热重分析仪、X射线光电子能谱仪、傅里叶变换红外光谱仪和扫描电子显微镜等设备表征两种阻燃剂的阻燃效果。研究结果表明,两种阻燃剂都能促进沥青表面生成具有阻燃效果的致密氧化层,从而起到阻燃作用。阻燃沥青热解产物中C―O和O＝C特征峰强度比纯沥青的大。无机阻燃剂质量分数为8%、有机阻燃剂质量分数为10%时,阻燃效果较好,并且有机阻燃剂的效果要优于无机阻燃剂。有机阻燃剂在热解前期就可以减少一部分芳香分和饱和分的挥发,同时,由于阻燃剂的黏连效果,氧化阻燃层较无机阻燃剂的更加致密。     

Nd对AJ61镁合金微观组织及腐蚀性能的影响

采用真空熔炼、氩气保护的方法制备了AJ61-xNd镁合金,研究了稀土元素Nd对AJ61镁合金微观组织的影响规律.采用静态失重法、极化曲线法研究了AJ61-xNd镁合金在3.5%NaCl溶液中的腐蚀行为.实验结果表明:随着Nd的加入,合金中出现Al2Nd、Al3Nd新相,合金晶粒得到细化,当Nd的质量分数为0.5%时合金晶粒最细.稀土元素Nd的加入显著降低了AJ61合金的腐蚀速度和腐蚀电流,提高了AJ61镁合金的平衡电位和腐蚀电位,显著改善了合金的耐腐蚀性能.在本实验范围内,当Nd质量分数为0.5%时,实验合金的耐腐蚀性能最好.     

AZ91D镁合金微弧阳极氧化及表面处理研究

采用微弧阳极氧化技术在AZ91D镁合金表面获得多孔结构的氧化膜,用不同方法对所得氧化膜进行表面后处理以提高其防腐蚀性能.用扫描电镜和电化学方法对阳极氧化膜的形貌和防腐蚀性能进行了研究,比较了不同表面处理方法的作用和效果.结果表明,采用水合及有机物封孔处理能够有效地封闭AZ91D镁合金微弧阳极氧化膜的微孔,使镁合金耐蚀性能显著提高.     

Al对HP40合金高温力学性能的影响

通过中频感应炉熔炼制备出铝质量分数分别为5%、7.5%、10%的HP40合金,在900℃下测试各合金的高温拉伸性能,并在扫描电镜下观察各合金的断口形貌.结果表明:随着Al质量分数的增加,合金的高温屈服强度、抗拉强度均先升高后降低,合金的延伸率先降低后增加.铝质量分数为5%的HP40合金具有最佳的高温力学性能,其900℃下的屈服强度为125MPa,抗拉强度为132MPa,延伸率为12%.     

C对Fe—20%Cr合金抗氧化性的影响

本文对不同含碳量的 Fe-20%Cr 合金进行了900℃静止大气气氛下的抗氧化实验,并测定了在此温度下的氧化动力学曲线.通过结合氧化膜表面微观形貌对氧化动力学曲线的分析,以及氧化膜下表层的微观分析等,指出随含碳量增加,氧化过程由良性的外部氧化转向恶性的内部氧化的过程及原因,并分析了合金中存在的两种主要类型的碳化物对氧化过程的影响.为高温磨损工况下材料的选择提供了一定的理论依椐.     

微弧氧化WE43镁合金人工髋关节摩擦磨损行为研究

在硅酸钠体系中对WE43镁合金人工髋关节进行微弧氧化,采用扫描电镜（SEM）观察微弧氧化膜层表面微观形貌,进而进行摩擦磨损性能试验,探讨其磨损机制。结果表明,经微弧氧化后可得到生长均匀、致密的氧化层;微弧氧化膜层具有一定的减摩效果和抗循环疲劳的能力,抗磨效果良好;微弧氧化WE43镁合金在低中载荷下磨损机制为磨粒磨损,高载荷下为磨粒磨损与剥落磨损并存。     

微弧氧化时间对Ti6Al4V合金表面生物薄膜的影响

为了改善钛合金表面的生物学性能,试验采用微弧氧化的方法在Ti6A l4V合金的表面生成一层富含Ca和P的生物氧化薄膜.研究了在恒流模式下不同氧化时间对膜层的形貌、厚度、元素以及相的组成变化的影响.研究结果表明:随着氧化时间的增加,膜层逐渐变得凹凸不平;膜厚的增速变缓;Ca质量分数呈线性增长;P质量分数呈递减式增长;锐钛矿TiO2的相对含量先增长,然后逐渐减少.     

Effects of Zn content on the microstructure and the mechanical and corrosion properties of as-cast low-alloyed Mg–Zn–Ca alloys

The effects of Zn content on the microstructure and the mechanical and corrosion properties of as-cast low-alloyed Mg–xZn–0.2Ca alloys (x=0.6wt%, 2.0wt%, 2.5wt%, hereafter denoted as 0.6Zn, 2.0Zn, and 2.5Zn alloys, respectively) are investigated. The results show that the Zn content not only influences grain refinement but also induces different phase precipitation behaviors. The as-cast microstructure of the 0.6Zn alloy is composed of α-Mg, Mg₂Ca, and Ca₂Mg₆Zn₃ phases, whereas 2.0Zn and 2.5Zn alloys only contain α-Mg and Ca₂Mg₆Zn₃ phases, as revealed by X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses. Moreover, with increasing Zn content, both the ultimate tensile strength (UTS) and the elongation to fracture first increase and then decrease. Among the three investigated alloys, the largest UTS (178 MPa) and the highest elongation to fracture (6.5%) are obtained for the 2.0Zn alloy. In addition, the corrosion rate increases with increasing Zn content. This paper provides an updated investigation of the alloy composition–microstructure–property relationships of different Zn-containing Mg–Zn–Ca alloys.     

Effect of Mg and Si on infiltration behavior of Al alloys pressureless infiltration into porous SiCp preforms

The effect of Mg and Si additon to Al matrix on infiltration kinetics and rates of Al alloys pressureless infiltration into porous SiCp preform was investigated by observing the change of infiltration distance with time as the Al alloys infiltrate into SiCp preforms at different temperatures. The results show that infiltration of SiCp preforms by Al melt is a thermal activation process and there is an incubation period before the infiltration becomes stable. With the increase of Mg content in the Al alloys from 0wt% to 8wt%, the infiltration will become much easier, the incubation period becomes shorter and the infiltration rate is faster, but these effects are not obvious when the Mg content is higher than 8wt%. As for Si addition to the Al alloys, it has no obvious effect on the incubation period, but the infiltration rate increases markedly with the increase of Si content from 0wt% to 12wt% and the rate has no obvious change when the content is bigger than 12wt%. The effect of Mg and Si on the incubation period is related to the infiltration mechanism of Al pressureless infiltration into SiCp preforms and their impact on the infiltration rate is a combined result from viscosity and surface tension of Al melt and SiC-Al wetting ability.     

La对AlSi10Cu0.2Mg0.2Mn和ZnAl12Cu1(Mg)铸造合金力学性能的影响

利用Al-La中间合金制备了AlSi10Cu0.2Mg0.2Mn-x La和Zn Al12Cu1(Mg)-x La铸造合金,考察了不同的La含量对合金组织和抗拉强度、伸长率、冲击强度等性能的影响.研究结果表明:微量稀土La可以细化合金的晶粒,改变Si相晶粒大小和形状.与未添加La的合金相比,含有微量稀土La的AlSi10Cu0.2Mg0.2Mn-x La合金和Zn Al12Cu1(Mg)-x La合金具有更优良的力学性能.当AlSi10Cu0.2Mg0.2Mn铸造合金中La添加量为0.15%(质量分数)时,铸造合金的伸长率增加2.7倍.含有0.1%(质量分数)La的Zn Al12Cu1(M g)-x La合金抗拉强度和伸长率相比于未添加稀土La的合金,分别增强1.3倍和3.2倍.含有0.3%(质量分数)La时Zn Al12Cu1(Mg)-x La的硬度增强1.8倍,但冲击强度是含有0.15%(质量分数)La时最高.综合考虑Zn Al12Cu1(Mg)-x La铸造合金的机械性能,稀土La的最优添加量为0.1%~0.2%(质量分数).     

Hydrogen storage and low-temperature electrochemical performances of A2B7 type La-Mg-Ni-Co-Al-Mo alloys

The effect of Mo-addition on hydrogen storage and low-temperature electrochemical performances of La-Mg-Ni-Co-Al alloys is investigated. The alloys were synthetized via vacuum induction melting followed by annealing treatment at 1123 K for 8 h. The major phases in the annealed alloys are consisted of (La, Mg)2Ni7, (La, Mg)5Ni19 and LaNi5 phases. Mo-addition facilitates phase transformation of LaNi5 into (La, Mg)2Ni7 and (La, Mg)5Ni19 phases. Hydrogen absorption/desorption PCI curves indicates that the hydrogen storage capacity of the alloy increases remarkably with the addition of Mo. Furthermore, the La0.75Mg0.25Ni3.05Co0.2Al0.05Mo0.2 alloy shows excellent hydriding/dehydriding kinetics with a higher capacity, requiring only 100 s to reach its saturated hydrogen capacity of 1.58 wt% at low temperature of 303 K, and releasing 1.57 wt% hydrogen within 400 s at 338 K. Electrochemical experiments manifest that the Mo-added alloy electrode has perfect activation properties and the maximum discharge capacity. The low-temperature dischargeability shows that the La0.75Mg0.25Ni3.05Co0.2Al0.05Mo0.2 alloy exhibits the excellent low-temperature discharge performance, and the maximum discharge capacity is improved from 231.0 to 334.6 mAh/g at 253 K. The HRD property of the alloy electrode is enhanced, suggesting that Mo enhances the kinetic ability at low-temperature.     

High thermal conductivity and high strength magnesium alloy for high pressure die casting ultrathin-walled components

With the rapid development of 3 C industries,the demand for high-thermal-conductivity magnesium alloys with high mechanical performance is increasing quickly.However,the thermal conductivities of most common Mg foundry alloys(such as Mg-9 wt%-lwt%Zn) are still relatively low.In this study,we developed a high-thermal-conductivity Mg-4 Al-4 Zn-4 RE-1 Ca(wt%,AZEX4441) alloy with good mechanical properties for ultrathin-walled cellphone components via high-pressure die casting(HPDC).The HPDC AZEX444...     

MgZnCa合金的组织结构和力学性能分析

通过铜模吸铸法制备直径为3mm的Mg-Zn-Ca三元共晶合金,按成分比例配制的合金分别为Mg72Zn15Ca13、Mg62Zn36Ca2、Mg14Zn22Ca64和Mg26Zn48Ca26.利用X射线衍射仪(XRD)、光学显微镜(OM)、微机控制电子式万能试验机和扫描电子显微镜(SEM)对MgZnCa合金的组织结构、力学性能和断口形貌进行研究.结果表明:Mg72Zn15Ca13、Mg14Zn22Ca64和Mg26Zn48Ca26合金形成非晶相和晶体相共存的复合材料,Mg62Zn36Ca2形成纯晶体;其中强度最高、塑性最好的是Mg14Zn22Ca64,其强度和塑性应变分别为548MPa和0.9%;对于该合金系,强度随结晶度降低而升高;压缩断口形貌显示,Mg72Zn15Ca13、Mg62Zn36Ca2、Mg14Zn22Ca64和Mg26Zn48Ca26合金均为脆性断裂.     

Corrosion behavior of as-cast Mg–8Li–3Al+xCe alloy in 3.5wt% NaCl solution

Mg–8Li–3Al+xCe alloys (x = 0.5wt%, 1.0wt%, and 1.5wt%) were prepared through a casting route in an electric resistance furnace under a controlled atmosphere. The cast alloys were characterized by X-ray diffraction, optical microscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The corrosion behavior of the as-cast Mg–8Li–3Al+xCe alloys were studied under salt spray tests in 3.5wt% NaCl solution at 35°C, in accordance with standard ASTM B–117, in conjunction with potentiodynamic polarization (PDP) tests. The results show that the addition of Ce to Mg–8Li–3Al (LA83) alloy results in the formation of Al₂Ce intermetallic phase, refines both the α-Mg phase and the Mg₁₇Al₁₂ intermetallic phase, and then increases the microhardness of the alloys. The results of PDP and salt spray tests reveal that an increase in Ce content to 1.5wt% decreases the corrosion rate. The best corrosion resistance is observed for the LA83 alloy sample with 1.0wt% Ce.     

Corrosion mechanism of micro-arc oxidation treated biocompatible AZ31 magnesium alloy in simulated body fluid

The rapid degradation of magnesium(Mg) based alloys has prevented their further use in orthopedic trauma fixation and vascular intervention,and therefore it is essential to investigate the corrosion mechanism for improving the corrosion resistance of these alloys. In this work, the effect of applied voltage on the surface morphology and the corrosion behavior of micro-arc oxidation(MAO) with different voltages were carried out to obtain biocompatible ceramic coatings on AZ31 Mg alloy. The effects of applied voltage on the surface morphology and the corrosion behavior of MAO samples in the simulated body fluid(SBF) were studied systematically. Scanning electron microscope(SEM) and X-ray diffractometer(XRD)were employed to characterize the morphologies and phase compositions of coating before and after corrosion. The results showed that corrosion resistance of the MAO coating obtained at 250 V was better than the others in SBF. The dense layer of MAO coating and the corrosion precipitation were the key factors for corrosion behavior. The corrosion of precipitation Mg(OH)2and the calcium phosphate(Ca–P) minerals on the surface of MAO coatings could enhance their corrosion resistance effectively. In addition, the mechanism of MAO coated Mg alloys was proposed.     

ZM6 铸造镁合金表面斑点缺陷形成机理分析

目的 为探究 ZM6 铸造镁合金表面斑点缺陷产生的原因及其形成机理。 方法 通过扫描电子显微镜( SEM) 对未经机加工和经机加工后的 ZM6 铸造镁合金表面不同形态的斑点缺陷进行形貌分析,并结合能量色散 X 射线 谱(EDS)对斑点缺陷的化学成分进行检测,最后耦合合金铸态组织和力学性能进行综合分析。 结果 未经机加工的 ZM6 铸造镁合金表面斑点缺陷呈深黑色,而经机加工后的 ZM6 铸造镁合金表面斑点缺陷呈白色,且部分白色斑点 中心有一小块黑色区域。 不过未经机加工和经机加工后的 ZM6 铸造镁合金表面斑点缺陷都呈现龟裂状、其与基 体的过渡界面处均未发现任何空隙存在,且其主要成分均为 Mg 的氧化物或氢氧化物、同时含有 Cl、K 等由溶剂引 入的杂质元素,但未经机加工的 ZM6 铸造镁合金表面斑点缺陷中 Cl 元素的含量相对较高,而经机加工后的 ZM6 铸造镁合金表面斑点缺陷中 K 元素的含量相对较高。 值得指出的是,经机加工后的 ZM6 铸造镁合金表面白色斑 点中黑色区域存在微小气孔。 结论 ZM6 铸造镁合金表面斑点缺陷的产生是由 Mg 的化学腐蚀及电偶腐蚀造成的, 而不是由氧化夹杂造成的。 因此,通过加强 ZM6 铸造镁合金精炼效果以获得化学成分均匀的熔体是获得高质量 构件的有效途径。     

Ca对变形Mg-9Li-2Zn合金显微组织和机械性能的影响

实验熔制了Mg-9%Li-2%Zn(质量分数)合金并研究了添加质量分数为0.1%~0.5%的Ca对合金的影响.合金板材具有良好的冷加工性能,室温下可以轧成2 mm厚的薄板.研究了微量元素Ca对板材显微组织和机械性能的影响.室温下对板材进行拉伸测试,结果表明添加元素Ca能够提高合金的机械性能,当添加质量分数为0.1%的Ca时,板材的抗拉强度和延伸率分别提高了19%和6%,随着Ca含量的增加,强度略有提高而延伸率下降.通过显微观察可知,Ca对显微组织有细化作用,其中含Ca 0.1%时效果最明显.通过分析结果可知Ca在晶界处的吸附致使显微组织细化,进而影响了板材的机械性能.