Mg含量对Al-Si-Mg铸造合金微观组织与力学性能的影响

本文研究了Mg含量分别为0.00wt%、0.35wt%和0.70wt%的Al-7wt%Si-Mg铸造合金的微观组织和力学性能.通过变质处理和改变凝固速率,可观察到不同的微观组织.DSC试验分析了不同Mg含量合金中相的变化.结果表明,在较高Mg含量的合金中,未变质的共晶Si粗化,变质的共晶Si变质不完全.在Al-7wt%Si-0.70wt%Mg合金中,富Fe相是粗大的π相(Al9FeMg3Si5)和少量的针状β相(Al5FeSi).相反,在Al-7wt%Si-0.35wt%Mg合金中,富Fe相是针状的β相(Al5FeSi).随着合金中Mg含量的增加,合金的抗拉强度增大,延伸率却降低.     

(Si+Mn)/Fe对Al-5Cu合金铸态组织及力学性能的影响

在Al-5Cu-0.3Fe高强铸造合金中添加Mn和Si,采用OM、SEM、EDS及DSC等分析方法研究(Si+Mn)/Fe质量比(K=3、4、5和6)对其铸态组织及力学性能的影响。结果表明：随着K值的增大，富Fe相形貌的变化趋势为针状→汉字状→粗大汉字状富Fe相聚集，富Fe相由针状Al₃FeMn向汉字状Al₆FeMn转变。Al-5.0Cu-0.3Fe-1Si-xMn合金，K=4时，拉伸断口展现良好的塑性特征，合金的综合力学性能最佳，比K=3时抗拉强度和延伸率分别提高了22%和65%。Si和Mn元素对Al-5.0Cu-0.3Fe合金的富Fe相有良好的变质作用。适当减少Mn的添加量，而增加Si的含量，保持(Si+Mn)/Fe=4,有助于减少合金的孔洞缺陷，降低热裂敏感性，较好地调控富Fe相形貌和尺寸。     

RE、Mg及Ti对Zn-4.5%Al合金耐蚀性的影响

对Zn-4.5%Al合金中添加微量合金元素RE、Mg及Ti的微观组织及耐蚀性进行研究,对添加单元合金试样进行了金相观察和电化学测试。结果表明,当RE、Mg和Ti的含量分别为0.10%、0.10%和0.03%时,耐腐蚀性效果较为明显。在此基础上进行正交试验、SEM观察和中性盐雾腐蚀及电化学测试,结果表明,Zn-4.5%Al-0.10%RE-0.05%Mg-0.05%Ti合金具有优良的共晶组织和很好的耐腐蚀性能。     

高性能Al-5Mg-2Si-xCe合金的制备及其力学性能研究

以Al-5Mg-2Si合金为基体合金,通过掺杂稀土Ce元素对合金进行改性,制备了不同Ce掺量的Al-5Mg-2Si-xCe(x=0,0.2,0.4和0.6)合金。采用XRD、SEM、EDS和力学性能分析等方式,研究了合金的结构、微观形貌和力学性能。结果表明,Al-5Mg-2Si-xCe(x=0,0.2,0.4和0.6)合金主要由α相组合而成,掺杂Ce元素后出现了Al_8CeFe_4三元含铁相的化合物,说明Ce具有促进β-Fe相转化成α-Fe相Al_8CeFe_4的作用;不掺杂Ce元素的Al-5Mg-2Si合金的枝晶排列紊乱且尺寸较为粗大,掺入稀土Ce元素后,枝晶的排列得到了明显改善,并且随着Ce掺量的增加,晶粒逐渐细化,分布更为均匀,α-Al的尺寸也逐渐缩小;当Ce掺量为0.4%(质量分数)时,合金的抗拉强度和延伸率均达到最佳,分别为133.70 MPa和1.64%,相比Ce掺量为0时,分别增长了26.49%和115.79%;未掺杂Ce的合金主要为解离断裂,掺入Ce后,合金的断裂方式主要为延晶断裂,且断口处晶粒均较为完整未被拉裂。     

冷却速度及铝含量对含Nd的Zn-Al合金组织和耐蚀性的影响

采用扫描电镜(SEM)和能谱(EDS)分析以及电化学极化和中性盐雾试验(NSS)等手段,研究了Zn-x Al(x=4%,5%,7%)-0.06%Nd合金在炉冷,空冷,水冷(冷却速度分别为0.03,1.08和40℃/s)条件下的凝固组织与耐蚀性。结果表明:随着冷却速度的增加,合金组织不断细化,共晶组织的层片间距不断减小,而耐腐蚀性先增大后减小,且稀土Nd的添加有利于进一步减小共晶层片间距和提高合金的耐腐蚀性能。空冷条件下获得的Zn-5%Al-0.06%Nd合金的耐蚀性最佳。Al含量在4%~7%之间变化时,主要引起合金组织的变化,而对合金耐腐蚀性影响不大。     

硅含量对热浸镀Zn-40%Al合金层凝固组织及耐蚀性的影响

为了改善Zn-40%Al合金热浸镀层的性能,在Zn-40%Al合金中加入了Si,研究了不同硅含量对Zn-40%Al合金镀层凝固组织及耐蚀性的影响。结果表明:当硅含量在0.5%～1.5%时,随着硅的增加,镀层凝固组织中的铝硅共晶组织不断增多,富铝相晶粒不断被细化,富铝枝晶相排列越来越规则,镀层的耐蚀性不断增强;当硅达到2.0%时,镀层会出现漏镀缺陷;硅的加入能在镀层表面形成具有优良腐蚀性的Al3.21Si0.47,有利于镀层耐蚀性的提高。     

稀土元素Ce对Sr变质的Al-5Si铝合金焊丝含氢量和焊缝气孔率的影响

通过减压凝固法、固态测氢法和X射线检测分别研究了稀土元素Ce对Sr变质的Al-5Si铝合金焊丝熔体吸氢倾向、焊丝合金含氢量和焊缝气孔率的影响。结果表明,单独添加0. 02%(质量分数)的Sr时,Al-5Si合金焊丝含氢量和焊缝气孔率显著增加。当向含0. 02%Sr的Al-5Si合金中添加0%～0. 05%(质量分数)的Ce时,Al-5Si-0. 02Sr-x Ce合金焊丝含氢量随着Ce含量的增加而降低,并在Ce含量为0. 05%时达到最低值0. 07 m L/(100 g Al),较Al-5Si-0. 02Sr合金焊丝降低了81. 6%。进一步增加Ce的含量至0. 1%,合金焊丝含氢量基本不变。随Ce含量的增加,焊缝的气孔率与合金焊丝含氢量的变化趋势基本一致,而且对于Ce含量大于等于0. 05%的焊丝,其焊接形成的焊缝接头无气孔。Ce的添加对焊接接头的拉伸性能几乎没有影响,但是明显提高了焊接接头的弯曲性能。     

Sb对Mg-3Sn-1.5Al-1Zn-1.2Si合金组织性能的影响

在熔炼过程中以单质形式加入Sb,研究了0~1.8%(质量分数,下同)范围内不同含量的Sb对Mg-3Sn-1.5Al-1Zn-1.2Si合金显微组织和力学性能的影响。结果表明,Sb能与Mg基体优先生成Mg3Sb2相,加入1.0%的Sb对Mg2Si相的汉字状结构变质作用显著,Mg2Si中的Si能与Sn发生取代反应,生成富Sn的Mg2(Si,Sn)。随着Sb的增加,铸态合金和挤压态合金的延伸率逐渐减小,而抗拉强度呈现先增加后降低的趋势,塑性和强度的最佳配合点约为1.0%,Sb含量的增加有利于改善Mg-3Sn-1.5Al-1Zn-1.2Si合金的耐热性能。     

Sb对Mg-3Sn-1.5Al-1Zn-1.2Si合金组织性能的影响

在熔炼过程中以单质形式加入Sb,研究了0~1.8%(质量分数,下同)范围内不同含量的Sb对Mg-3Sn-1.5Al-1Zn-1.2Si合金显微组织和力学性能的影响。结果表明,Sb能与Mg基体优先生成Mg3Sb2相,加入1.0%的Sb对Mg2Si相的汉字状结构变质作用显著,Mg2Si中的Si能与Sn发生取代反应,生成富Sn的Mg2(Si,Sn)。随着Sb的增加,铸态合金和挤压态合金的延伸率逐渐减小,而抗拉强度呈现先增加后降低的趋势,塑性和强度的最佳配合点约为1.0%,Sb含量的增加有利于改善Mg-3Sn-1.5Al-1Zn-1.2Si合金的耐热性能。     

添加稀土铈对热浸镀铝45钢的组织及其性能的影响

采用SEM和XRD研究了添加不同含量铈对45钢基热浸镀铝镀层及其退火后的组织和结构影响,并用氧化增重法考察了镀层的耐热性,用M-2000型摩擦磨损试验机测试了镀层退火后的耐磨性能。结果表明,镀液中稀土铈质量分数为0.1%~0.25%时,镀层晶粒细化、厚度降低,退火合金层厚度增加。稀土铈能抑制合金层的Fe2Al5相生长,使镀层合金层以FeAl3、少量Fe2Al5相为主,使退火合金层以FeAl、Fe3Al相为主。稀土铈含量为0.25%时,镀层的抗高温氧化性和镀层退火后在油润滑下的耐磨性最佳。     

新型Mg-8Li-5Al-5Ca合金的微观组织、力学及耐腐蚀性能

设计了新型高钙铝比Mg-8Li-5Al-5Ca合金,通过常温拉伸、失重法、pH测定和电化学测试等方法研究了合金的常温力学性能和耐腐蚀性能。采用扫描电镜(SEM)和X射线衍射(XRD)分析了基体和腐蚀产物相结构、合金显微组织以及腐蚀形貌。研究结果表明,这种镁锂合金形成Al2Ca相包围双基体(α-Mg+β-Li)的结构,挤压后基体组织和第二相粒子均明显细化。Mg-8Li-5Al-5Ca合金的耐腐蚀性能优于一般镁锂合金,且随着挤压比的增大进一步提升。该合金的力学性能协调了镁锂合金的优良塑性和高钙铝比镁合金的高强度,拥有较高的抗拉强度(222 MPa)和延伸率(8.3%)。     

The microstructure,mechanical properties and corrosion behaviour of Ce-containing Mg-3Sn-1Ca alloy

The effects of minor Ce on the microstructure, mechanical properties and corrosion behaviour of Mg-3Sn-1Ca alloy are investigated systematically. The minor Ce can refine the eutectic structure between α-Mg and CaMgSn and make the microstructure more uniform. The maximum ultimate tensile strength and elongation of the alloy with the Ce content of 0.3?wt-% were 152.5?MPa and 4.1%, respectively. Meanwhile, the corrosion resistance of the Ce-containing alloys is improved by Tafel curves and electrochemical impedance spectra, especially when the Ce is up to 0.3?wt-%. The minor Ce can promote the formation of the surface film and makes the corrosion product film to become more compact, which effectively prevents further the occurrence of corrosion of the Mg matrix.     

镁含量和硅对铁-锌铝镁合金固-液扩散偶中Fe-Al反应层的影响

在热浸镀锌中,铁基表面Fe-Al化合物层的形成会影响镀层的生长和质量。将Fe/(Zn-11%Al-3%Mg)和Fe/(Zn-11%Al-x%Mg-0.2%Si)扩散偶在600℃下进行25min的固-液扩散实验,利用扫描电子显微镜(SEM)和能谱仪(EDS)研究了镁含量和硅对铁-锌铝镁合金固-液界面Fe-Al合金层形成的影响。结果表明,Fe/(Zn-11%Al-3%Mg)固-液扩散偶反应层由FeAl3和Fe2Al5相层组成;随着Mg含量的增加,Fe/(Zn-11%Al-x%Mg-0.2%Si)扩散偶中反应层的厚度呈现先增加后减少再增加的变化趋势,当镁含量为3%时反应层厚度最薄;Fe/(Zn-11%Al-3%Mg)扩散偶中Fe-Al反应层的平均厚度比Fe/(Zn-11%Al-3%Mg-0.2%Si)扩散偶中反应层的厚度大60μm,证明Si元素起到抑制Fe-Al反应层形成的作用。研究结果为解释Super Dyma合金镀层中不形成明显的Fe-Al抑制层提供了实验依据。     

Ce对铸态5356铝合金组织性能的影响

为探索稀土元素Ce对5356铝合金组织性能的影响,本文采用气泡浮游法,通过添加不同成分微量的稀土元素Ce精炼制备出含Ce不同含量的5356铝合金,通过显微组织观察、室温拉伸试验、密度测试等方法研究了在5356铝合金基体中添加稀土元素Ce对其组织性能的影响.实验结果表明:合金的力学性能及密度随着Ce添加量的增加而得到改善;稀土元素Ce既能够提高合金的抗拉强度、断后伸长率及硬度等力学性能,又能够提高合金的致密度使得铸锭中的气孔或疏松减少;添加Ce质量分数为0.4%时,其力学性能改善效果最佳,抗拉强度达到245.8 MPa,屈服强度为101.24 MPa,断后伸长率增加至29.05%,其密度也达到最大,相对提高了0.67%.     

Effect of minor content of Gd on the mechanical and degradable properties of as-cast Mg-2Zn-xGd-0.5Zr alloys

RE-containing Mg alloys used as biodegradable medical implants exhibit good promising application due to their good mechanical properties and degradation resistance. In this work, effect of Gd on the microstructure, mechanical properties and biodegradation of as-cast Mg-2Zn-xGd-0.5Zr alloys was investigated. The results showed that there were mainly α-Mg, I-phase, W-phase and MgZn2 phase in Mg-Zn-Gd-Zr alloys. With increase of the Gd content, the strength of the alloys was enhanced due to the second phase strengthening and grain refinement. The degradation resistance of Mg-2Zn-0.5Zr alloy was increased by adding 0.5%–1% Gd due to the uniformly distributed second phases which acted as a barrier to prevent the pitting corrosion. However, increasing Gd content to 2% reduced the degradation resistance of the alloy due to the galvanic corrosion between the matrix and the second phases.The good degradation resistance and mechanical properties of as-cast Mg-2Zn-1Gd-0.5Zr alloy makes it outstanding for biomaterial application.     

Binary Zn-Ti alloys for orthopedic applications: Corrosion and degradation behaviors,friction and wear performance,and cytotoxicity

Zinc (Zn) and its biocompatible and biodegradable alloys have substantial potential for use in orthopedic implants.Nevertheless,pure Zn with a hexagonal close-packed crystal structure has only two independent slip systems,therefore exhibiting extremely low elongation and yield strength in its ascast condition,which restricts its clinical applications.In this study,as-cast Zn-xTi (titanium) (x =0.05,0.10,0.20,and 0.30 wt.％) binary alloys were hot-rolled and their microstructures,mechanical properties,wear resistance,and cytocompatibility were comprehensively investigated for orthopedic implant applications.The microstructures of both as-cast and hot-rolled Zn-xTi alloys consisted o fan α-Zn matrix phase and a TiZn16 phase,while Zn-0.2Ti and Zn-0.3Ti exhibited a finer α-Zn phase due to the grainrefining effect of Ti.The hot-rolled Zn-0.2Ti alloy exhibited the highest yield strength (144.5 MPa),ultimate strength (218.7 MPa),and elongation (54.2％) among all the Zn-xTi alloys.The corrosion resis-tance of Zn-xTi alloys in Hanks' solution decreased with increasing addition of Ti,and the hot-rolled Zn-0.3Ti alloy exhibited the highest corrosion rates of 432 μm/y as measured by electrochemical testing and 57.9 μm/y as measured by immersion testing.The as-cast Zn-xTi alloys showed lower wear losses than their hot-rolled counterparts.The extracts of hot-rolled Zn-xTi alloys at concentrations of ≤ 25％ showed no cytotoxicity to MG-63 osteosarcoma cells and the extracts of Zn-xTi alloys exhibited enhanced cytocompatibility with increasing Ti content.     

Microstructural evolution,mechanical properties and corrosion behavior of as-cast Mg-5Li-3Al-2Zn alloy with different Sn and Y addition

Influences of Sn and Y on the microstructure,mechanical properties,and corrosion behavior of as-cast Mg-5Li-3Al-2Zn (LAZ532) alloy were investigated.The addition of Sn and Y refines grains and results in the formation of Mg2Sn and Al2Y phases,thus improving the mechanical properties of alloy by second phase strengthening and grain refinement strengthening.As-cast LAZ532 alloy shows typical filiform corrosion morphology,and the addition of Sn and Y does not change the corrosion mode of alloy.Ascast LAZ532-0.8Sn-1.2Y alloy shows excellent mechanical properties with yield strength of 166.2 MPa,ultimate tensile strength of 228.6 MPa and elongation of 14.8 ％,and exhibits the best corrosion resistance with the smallest corrosion current density and the lowest anodic dissolution rate.     

Effect of Oxide Inclusions on Electrochemical Properties of Aluminium Sacrificial Anodes

Oxide films are incorporated into melts by an entrainment process, and are expected to be present in most metals, but particularly cast Al alloys. The oxides are necessarily present as folded-over double films (bifilms) that are effectively cracks. Their effect on the electrochemical behaviour of cast Al-5Zn-0.02ln sacrificial anodes was studied in 3 wt pct sodium chloride solution using the NACE efficiency evaluation. Three methods were employed to entrain progressive amounts of oxide in the alloy, including the addition of Al-Zn-ln maching chips to the charge, increasing the pouring height, and agitating the melt. The introduction of oxide bifilms in the cast alloy resulted in the deterioration of the electrochemical properties of the sacrificial anodes, such as current capacity and anode efficiency, and introduced increasing variability in these properties. The results suggest that corrosion behaviour is strongly related to the presence of bifilms suspended in the liquid alloy because bifilms provide crack paths allowing the corrodant to penetrate deeply into the metal matrix, and simultaneously provide localized galvanic cells because of the precipitation of Fe rich intermetallic compounds on their outer surfaces.     

添加Al-5Ti-B和Al-2Zr-Er对铸态铝锌镁合金力学性能的影响

铝锌镁合金以其优异的力学性能广泛应用于航空、航天、交通运输等工业领域,而铝合金的细化一直是铝加工行业的研究重点.为细化晶粒并提高其力学性能,本文将传统细化剂Al-Ti-B与RE复合添加到铝锌镁合金中,借助于XRD、光学显微镜、扫描电镜、拉伸实验等测试方法研究了不同细化剂对Al7Zn2.4Mg合金组织及其力学性能的影响.试验结果表明,合金中加入Al-5Ti-B和Al-Zr-Er后细化效果明显,单独添加Al-Ti-B的细化效果最好,但仍有少部分的晶粒保留的树枝晶形态.随着Al-Ti-B和Al-Zr-Er添加量的增多,合金的晶粒发生明显变化,塑性也随之增加,其中,添加0.4wt.%Al-5Ti-B细化剂对合金的塑性影响最大,而抗拉强度呈先增大后减小的趋势,复合添加0.2wt.%Al-2Zr-Er和0.2wt.%Al-5Ti-B细化剂的合金晶粒圆整且未出现树枝晶,晶界析出物最少平均抗拉强度最高.Al-Ti-B和Al-Zr-Er均可细化铸态铝锌镁合金的晶粒,同时添加两种细化剂更有利于提高合金的综合力学性能.     

Mechanical properties,degradation performance and cytotoxicity of Mg–Zn–Ca biomedical alloys with different compositions

In this paper, ternary Mg–Zn–Ca magnesium alloys were investigated as degradable biomedical material. Tensile results showed that the mechanical properties of the alloys can be modulated by controlling Zn content. With increasing Zn contents, yield strength (YS), ultimate tensile strength (UTS) and ductility of the materials are increased at first and then decreased. In-vitro corrosion tests in Hank's simulated body fluid presented that the composition and microstructure of Mg–Zn–Ca alloys strongly affected their corrosion behavior. An increasing content of Zn element can lead to a high corrosion potential and bad corrosion resistance. The cytotoxicity evaluated by neutral red kits on L-929 cells revealed that Mg-1.0 Zn-1.0Ca, Mg-2.0 Zn-1.0 Ca, and Mg-3.0 Zn-1.0 Ca alloys did not induce toxicity in cells.