Effects of silicocalcium on microstructure and properties of Mg-6Al-0.5Mn alloy

1 Introduction Magnesium alloys are attractive for applications in the automobile, aerospace and electronic industries due to their light mass, high stiffness, high specific strength, good dimensional stability and damping capacity. It is the lightest sp…     

硅钙合金对AM60镁合金流动性的影响

研究了硅钙合金对AM60合金流动性的影响,结果表明:硅钙合金能改善合金的铸造性能,降低合金的结晶温度间隔,提高合金的流动性,当加入1.8%的硅钙合金时,合金的流动性提高了51.7%;加入硅钙合金后,合金中形成了稳定性较高的Mg2Si颗粒,显著细化了合金的显微组织,第二相也逐渐趋于弥散分布.     

MgCO3及Sr对过共晶AM60B-2．0％Si复合材料变质的研究

研究了Sr、MgCO3对过共晶AM60B-2．0％Si镁基复合材料中Mg2Si相及基体的复合变质作用。结果表明：Sr的加入量是决定其能否对复合材料中的Mg2Si相有效变质的重要因素。未变质的初生Mg2Si呈粗大的树枝状,经变质后转为多角形状;未变质的共晶Mg2Si呈粗大的汉字状,经变质后变为弥散而细小的短棒状或多边形粒状。同时,经MgCO3复合变质后,复合材料基体组织也得到了较好的细化,从而改善了复合材料的力学性能。     

纳米SiC颗粒增强AM60镁合金组织性能的研究

通过对纳米SiC颗粒的预处理,使用搅熔复合铸造工艺,制备了纳米SiC颗粒增强AM60铸造镁合金材料.研究了纳米SiC颗粒对镁合金的显微组织、力学性能和硬度等的影响.结果表明,在镁合金中添加纳米SiC颗粒能够细化其组织,提高材料的综合力学性能.当纳米SiC颗粒加入量(体积分数)为1.0%时,纳米颗粒增强AM60镁合金的抗拉强度、伸长率和硬度(HB)分别达到240 MPa、16.0%和53.9,较相同工艺下未加纳米颗粒的AM60分别提高了12.1%、40.3%和11.6%.同时对纳米SiC颗粒对镁合金的强化机理进行了探讨.     

Comparison of corrosion behaviors of AZ31, AZ91, AM60 and ZK60 magnesium alloys

The corrosion behaviours of four kinds of rolled magnesium alloys of AZ31, AZ91, AM60 and ZK60 were studied in 1 mol/L sodium chloride solution. The results of EIS and potentiodynamic polarization show that the corrosion resistance of the four materials is ranked as ZK60＞AM60＞AZ31＞AZ91. The corrosion processes of the four magnesium alloys were also analyzed by SEM and energy dispersive spectroscopy(EDS). The results show that the corrosion patterns of the four alloys are localized corrosion and the galvanic couples formed by the second phase particles and the matrix are the main source of the localized corrosion of magnesium alloys. The corrosion resistance of the different magnesium alloys has direct relationship with the concentration of alloying elements and microstructure of magnesium alloys. The ratio of the β phase in AZ91 is higher than that in AZ31 and the β phase can form micro-galvanic cell with the alloy matrix, as a result, the corrosion resistance of AZ31 will be higher than AZ91. The manganese element in AM60 magnesium alloy can form the second phase particle of AlMnFe, which can reduce the Fe content in magnesium alloy matrix, purifying the microstructure of alloy, as a result, the corrosion resistance of AM60 is improved. However, due to the more noble galvanic couples of AlMnFe and matrix, the microscopic corrosion morphology of AM60 is more localized. The zirconium element in ZK60 magnesium alloy can refine grain, form stable compounds with Fe and Si, and purify the composition of alloy, which results in the good corrosion resistance of ZK60 magnesium alloy.     

增强颗粒对镁基复合材料磨损性能的影响(英文)

研究增强颗粒Mg2Si对镁基复合材料摩擦磨损性能的影响,讨论Si加入量、载荷和滑动速度对Mg2Si/AM60镁基复合材料磨损性能的影响。结果表明,向镁合金中加入合金元素Si,可原位生成增强颗粒Mg2Si,增强颗粒Mg2Si可明显提高AM60镁合金的磨损性能。随着载荷和滑动速度的增加,AM60镁合金和Mg2Si/AM60镁基复合材料的磨损量都增大。AM60镁合金的磨损机制为粘着磨损。随着载荷的增大,Mg2Si/AM60镁基复合材料的磨损由磨粒磨损向粘着磨损转变。     

真空条件下Nd对AM60镁合金组织与性能的影响

研究了稀土Nd对AM60镁合金组织的影响,并分析析出相及其对合金力学性能的影响.结果表明,在AM60合金中加入稀土Nd元素能有效地细化合金组织,使Mg17A112相分离变细;Nd元素优先与合金中的A1元素反应生成二元高熔点A111Nd3相:适量的稀土Nd能有效提高合金的抗拉强度、屈服强度和延伸率;过量的稀土Nd则会消耗合金中更多的A1元素和导致A111Nd3相粗化,使合金的力学性能下降;力学性能测试结果表明,AM60-0.9Nd具有最高的抗拉强度(230 MPa)、最高的屈服强度(127 MPa)和最高延伸率(14%),分别比基体合金提高28%、48%和250%.     

压铸Mg-5Al-xSi合金的组织与性能

研究了以AM50镁合金为基体，Si的质量分数分别为0.5％、0.93％和1.91％时的3种镁合金在压铸状态下的显微组织、流动性、力学性能和断裂特征。在含硅合金中观察到2种不同形貌的Mg2Si相，即多边形颗粒状与大块汉字状。Si元素能改善镁合金的流动性，提高合金硬度，但过高时（〉0．93％）会导致合金的室温力学性能下降。拉伸试样断面表现为脆性的解理或准解理断裂。     

Sb变质对Mg_2Si/AM60镁基复合材料组织及性能的影响

研究了Sb对Mg2Si增强相及基体组织的细化效果及机理。结果表明,Sb加入可生成Mg3Sb2,Mg3Sb2能够作为Mg2Si的异质核心,使得Mg2Si由汉字状变成颗粒状,并弥散地分布。同时,基体组织也得到细化,改善了合金的力学性能。加入0.8%的Sb后,合金的抗拉强度提高了12.2%。     

稀土Nd含量对AM60镁合金耐蚀性能的影响

AM60合金中加入稀土Nd可使晶粒细化,具有强化晶界和相界的作用,主要是通过提高基体电极电位来改善镁合金的耐腐蚀性能,加入Nd可阻隔活化Mg与H⁺的接触面积,同时抑制了Mg₁₇Al₁₂ 相对α相腐蚀的促进作用,加强了新相Al₁₁Nd₃和Mg₁₇Al₁₂相对镁合金腐蚀的阻碍作用,从而提高镁合金的耐腐蚀性能。     

Mg元素对强流脉冲电子束改性后Al-20Si合金表面微观组织及性能的影响

目的通过添加Mg元素改善Al-20Si合金的组织,提升其表面力学性能。方法运用场发射扫描电镜(FESEM)、显微硬度计及多功能材料表面性能试验仪等一系列检测手段,考察Mg元素对强流脉冲电子束改性Al-20Si合金表面效果的影响,及合金表面微观组织和表面力学性能的变化。结果 Mg元素能与硅相形成更细小的Mg_2Si相来细化初生硅相,同时可改善强流脉冲电子束处理后铝硅合金表面产生的微裂纹。材料表面经强流脉冲电子束改性后,所有的衍射峰发生了宽化及偏移。两组合金铝基体的显微硬度随着脉冲数的增加而逐渐递增,Al-20Si合金铝基体的显微硬度由745.5MPa增加到2170.7MPa,Al-20Si-5Mg合金的铝基体显微硬度由1061.3 MPa增加到2403.6 MPa,Mg元素的添加可提高Al-20Si合金的硬度。另外,通过往复摩擦试验发现,Mg元素及强流脉冲电子束都能提高材料的耐磨性。结论 Mg元素能改善强流脉冲电子束处理后Al-20Si合金表面的微观组织,添加Mg元素后,Al-20Si合金表面的力学性能得到提高。     

稀土元素Ce和La合金化对AM60镁合金腐蚀行为的影响

采用电子探针-能谱分析,场发射扫描电镜X射线衍射等方法研究了稀土元素Ce和La合金化对AM60镁合金结构和耐蚀性能的影响.结果表明,Ce和La的加入可在AM60镁合金中形成了富含稀土元素的γ相（MgAlRE）;能有效抑制析氢,提高镁合金的耐蚀性能;改善镁合金在含Cl-溶液中的耐蚀性能;腐蚀产物膜的晶态主要成分为铝和锰的氧化物,并含有少量的稀土氧化物和氢氧化物.     

Effect of addition of Si on microstructure,mechanical properties,bio-corrosion and cytotoxicity of Mg-6Al-1Zn alloy

The Mg-6Al-4Zn alloy was fabricated by mechanical alloying (MA) and hot pressing to serve as biodegradable metal implant. The influence of addition of 1% Si (mass fraction) on the microstructure, mechanical properties and bio-corrosion behavior of Mg-6Al-1Zn alloy was studied using X-ray diffractometry, transmission electron microscopy, compression test, as well as immersion, electrochemical test and MTT assay. The results showed that the addition of 1% Si to Mg-6Al-1Zn alloy led to the formation of fine Mg₂Si phase with polygonal shape, and increased compressive strength, elongation and improved corrosion resistance. Furthermore, the cell viability of Saos-2 cells has been improved by addition of 1% Si to Mg-6Al-1Zn alloy. According to the results, the magnesium ions released in the methylthiazol tetrazolium (MTT) test have not shown any cell toxicity. All these indicated that the addition of 1% Si improved the properties of Mg-6Al-4Zn alloy for using as a biodegradable implant.     

Influence of Sb modification on microstructures and mechanical properties of Mg2Si/AM60 composites

The refining effect and mechanism of Sb on Mg2Si and the microstructure of the matrix were investigated. The results indicate that there are Mg3Sb2 particles in the composites with the addition of Sb, and Mg3Sb2 can promote the formation of fine polygonal type Mg2Si by providing nucleation site. Meanwhile, the grain size of Sb modified alloy is finer than that of the matrix. The improved microstructure results in the improvement of mechanical properties. The ultimate tensile strength is increased by 12.2% with the addition of 0.8% Sb.     

MgCO3及Sr对过共晶AM60B-2.0％ Si复合材料变质的研究

研究了Sr、MgCO3对过共晶AM60B-2.0%Si镁基复合材料中Mg2Si相及基体的复合变质作用.结果表明:Sr的加入量是决定其能否对复合材料中的Mg2Si相有效变质的重要因素.未变质的初生Mg2Si呈粗大的树枝状,经变质后转为多角形状;未变质的共晶Mg2Si呈粗大的汉字状,经变质后变为弥散而细小的短棒状或多边形粒状.同时,经MgCO3复合变质后,复合材料基体组织也得到了较好的细化,从而改善了复合材料的力学性能.     

7A60铝合金点蚀行为的电化学噪声和电化学阻抗谱表征

采用电化学阻抗谱（EIS）和电化学噪声（EN）方法研究回归再时效（RRA）热处理状态下7A60铝合金的点蚀行为,通过扫描电子显微镜（SEM）和能谱仪（EDS）观察和分析合金的组织和第二相颗粒成分。结果表明,7A60铝合金在3.5%Na Cl溶液中存在两个腐蚀阶段,并且可以用EIS出现两个电容时间常数的时间和由EN计算出的小波分形维数D的变化来表征。SEM和EDS分析结果表明,在7A60铝合金中,严重的点蚀主要是由阳极相Mg Zn2引起的,其次是Al2MgC u和Mg2Si相,Al7Cu2Fe相对7A60铝合金点蚀行为的影响不大。     

Effect of Gd on microstructure,mechanical properties,and corrosion behavior of as-homogenized Mg−8Li−3Al−2Zn−0.2Zr alloy

The microstructure observation, tensile test, electrochemical measurement, and corrosion morphology characterization were conducted to study the effect of Gd on the microstructure, mechanical properties, and corrosion behavior of as-homogenized Mg?8Li?3Al?2Zn?0.2Zr (LAZ832?0.2Zr) alloy. The addition of trace Gd can improve the mechanical properties of as-homogenized LAZ832?0.2Zr alloy by refining the microstructure, reducing the content of AlLi softening phase, and forming Al₂Gd strengthening phase. Meanwhile, the addition of trace Gd can weaken the microgalvanic corrosion between matrix phase and AlLi phase, inhibit the galvanic corrosion between α-Mg phase and β-Li phase, and result in the formation of dense oxide film containing Gd₂O₃, thereby improving the corrosion resistance of the alloy. When the Gd content is 1.0 wt.%, the alloy shows the best comprehensive properties with the ultimate tensile strength of 189.8 MPa, elongation of 42.3%, and corrosion rate (determined by hydrogen evolution) of 0.86 mm·a^?1.     

MgCO_3和Sr对原位Mg_2Si/AM60B复合材料的变质

研究了MgCO3、Sr对原位自生Mg2Si/AM60B复合材料中Mg2Si相及基体的复合变质作用。结果表明,微量Sr的加入可以明显改善Mg2Si相的形貌。初生Mg2Si由粗大的树枝状转为多角形状,共晶Mg2Si由粗大的汉字状变为弥散而细小的短棒状或多边形粒状。同时,MgCO3对AM60B基体也起到了很好的细化作用,从而使原位自生Mg2Si/AM60B复合材料的力学性能得到提高。     

Sb对原位Mg2Si/Mg复合材料组织的影响

利用Mg-Si二元合金结晶的特点，在普通重力铸造的条件下，制备了原位Mg2Si／Mg复合材料，着重研究了Sb对复合材料中Mg2Si增强相形态的影响。结果表明，在Mg-10Si合金中，加入质量分数为0．8％Sb，不仅促进Mg2Si的均匀形核，而且Sb偏析于Mg2Si的界面上，阻止了Mg2Si的进一步长大。原位Mg2Si的形态由粗大的树枝状转变成均匀分布的颗粒状，形成了较理想的Mg2Si颗粒增强Mg基复合材料的组织。     

硅对Mg2Si/ZM5复合材料组织和性能的影响

在真空感应炉中氩气保护下制备材料，采用OM，SEM，EDAX和XRD及拉伸试验，研究分析了硅对原位反应自生Mg2Si/ZM5复合材料铸态显微组织和性能的影响规律。结果表明，反应添加物Si在ZM5合金中形成了高熔点、高硬度的Mg2Si强化相，明显地提高了材料的室温与高温强度，如Si的质量分数为1.5％时，室温抗拉强度与屈服强度提高幅度分别可达20.1％和61.5％，Si的质量分数为1.0％时，高温抗拉强度与屈服强度提高幅度分别可达14.9％和25.7％；Mg2Si相的形貌随着硅含量的不同而变化，如Si的质量分数为0.5％时，主要生成细小短棒状或片状共晶Mg2Si相，Si的质量分数大于1％时，则出现了粗大块状或汉字状初生Mg2Si相和片状或短棒状的共晶Mg2Si相；由于所生成的Mg2Si相本身是一种脆性相，使得该材料呈现出解理断裂，降低了材料的塑性。