Sb低合金化对Mg—9Al基合金显微组织和力学性能的影响

研究了合金元素Ｓｂ 对Ｍｇ９Ａｌ０ ．８Ｚｎ（ＡＺ９１） 基合金显微组织和力学性能的影响。结果表明,Ｓｂ加入后改善了合金的铸态组织, 使粗大的树枝晶变得更细小、弥散,Ｓｂ 主要是以弥散的第二相Ｍｇ３Ｓｂ２ 的形式分布于基体中。由于该相致密, 熔点高, 热稳定性好, 强化了晶界, 使得合金室温和高温力学性能得到一定的改善, 尤其使得抗高温蠕变性能大幅度提高, 塑性并没有受到明显损害。     

晶粒细化对Cu-12.2Al-4.0Mn形状记忆合金加工性能的影响

测定了Ｃｕ１２ ．２Ａｌ４ ．０ Ｍｎ 形状记忆合金的塑性图, 研究了微量元素Ｎｉ, Ｃｏ 和Ｂ 对合金的显微组织和加工性能的影响。结果表明：１） 试验合金在７００ ℃～８００ ℃高温β相状态下具有非常 好的塑性加工性能, 而在室温则呈脆性断裂;２） 试验合金中加入少量的（Ｎｉ＋ Ｂ＋ Ｃｏ） , 可以细化合金的晶粒,提高合金的冷加工性能;３） 采用有利发挥合金塑性的加工方法, 则能提高该合金的冷加工性能     

机械合金化制取高强度镁基复合材料

镁是最轻的金属材料,但由于其强度、韧性和耐蚀性都低故而限制了它的广泛应用。为了改进镁的力学和化学性能,很早以来便已发现添加Ａｌ、Ｚｎ、Ｍｎ之类元素合金化的方法,能显著地改善镁合金的力学性能。还发现将纯镁粉同纳米级Ａｌ２Ｏ３、ＺｒＯ２或ＳｉＣ超细粉进行机械混合或机械合金化,所获得的陶瓷颗粒增强的镁基复合材料具有很高的力学性能。用机械合金化方法合成的Ｍｇ－Ｌｎ－ＴＭ非晶合金,室温强度要比晶态镁基合金高２～３倍,这类非晶合金经部分晶化处理还能进一步提高强度。本文研究了利用机械合金化方法就地合成的高强度…     

Sc对Al－Li－Cu－Mg－Zr合金组织与性能的影响

研究了Ｓｃ对Ａｌ—Ｌｉ—Ｃｕ—Ｍｇ—Ｚｒ合金的显微组织与拉伸性能的影响。结果表明，δ′（Ａｌ３Ｌｉ）和Ｓ′（Ａｌ２ＣｕＭｇ）仍为含Ｓｃ合金中的主要强化相，Ｓｃ细化了合金的晶粒，降低了δ′颗粒的长大速度，促进Ｓ′相的析出和均匀弥散分布，还使合金析出Ａｌ３Ｓｃ颗粒和Ａｌ３Ｌｉ／Ａｌ３Ｓｃ复合析出相颗粒，这两种颗粒都有益于合金的性能。因此，加入Ｓｃ后合金表现出良好的强塑性配合。     

Sc对Al—Li—Cu—Mg—Zr合金组织与性能的影响

研究了Ｓｃ对Ａｌ－Ｌｉ－Ｃｕ－Ｍｇ－Ｚｒ合金的显微组织与拉伸性能的影响，结果表明，δ＇（Ａｌ３Ｌｉ）和Ｓ＇（Ａｌ２ＣｕＭｇ）仍为含Ｓｃ合金中的主要强化相，Ｓｃ细化了合金的晶粒，降低了δ＇颗粒的长大速度。促进了Ｓ＇相的析出和均匀弥散分布，还使合金析出Ａｌ３Ｓｃ颗粒和Ａｌ３Ｌｉ／Ａｌ３Ｓｃ复合析出相颗粒，这两种颗粒都有益于合金的性能，因此，加入Ｓｃ后合金表现出良好的强塑性配合。     

氮化硅陶瓷烧结过程中玻璃相的自动析晶

发现了Ｓｉ３Ｎ４ＭｇＯＣｅＯ２系陶瓷在烧结过程中玻璃相自动析晶现象。对于Ｓｉ３Ｎ４ＭｇＯＣｅＯ２系陶瓷,在１４５０℃,ＭｇＯＣｅＯ２与Ｓｉ３Ｎ４颗粒表面的ＳｉＯ２反应形成硅酸盐液相,冷却后成为玻璃相保留在烧结体中;当烧结温度高于１５５０℃时,发现ＣｅＯ２仍留在玻璃相中,但ＭｇＯ会自动析晶出来,其结果是大大减少了烧结体中严重影响其高温性能的玻璃相的含量,ＭｇＯＣｅＯ２是氮化硅陶瓷很理想的烧结助剂。     

微量硼和应变速率对变形TiAl合金室温力学性能的影响

以形变Ｔｉ４７Ａｌ２Ｍｎ２Ｎｂ合金为对象,研究了微量硼合金化和应变速率对ＴｉＡｌ合金室温力学性能的影响。发现添加微量（１．０％,摩尔分数）硼就能有效地细化形变Ｔｉ４７Ａｌ２Ｍｎ２Ｎｂ合金的近全片层组织,显著提高其室温强度,并在一定程度上改善室温塑性;变形ＴｉＡｌ合金不论添硼与否,其室温强度均随应变速率的升高而升高,而延伸率对应变速率不太敏感;微量硼合金化和应变速率对变形ＴｉＡｌ合金室温断裂方式无明显影响。     

内氧化粉体制备的Ag-SnO2接点材料的显微结构

Ａｇ－Ｓｎ－Ｍ（Ｍ＝Ｂｉ、Ｃｕ）合金粉末内氧化后经压制、烧结、挤压、加工制备成Ａｇ－ＳｎＯ２接点材料,用光学显微镜,Ｘ射线衍射和ＳＥＭ研究其显微结构,结果表明：在Ａｇ－ＳｎＯ２材料中存在Ａｇ,ＳｎＯ２、Ｂｉ２ＳｎＯ７和ＣｕＯ,氧化物以极细小的颗粒分布在银基体中。     

颗粒增强Al－4％Mg复合材料中显微孔隙的分析

探讨了Ａｌ２Ｏ３、ＳｉＣ、ＳｉＯ２等三种颗粒增强Ａｌ－４％Ｍｇ复合材料凝固组织中显微孔隙的形成规律．结果表明：前者显微孔隙是由Ａｌ２Ｏ３颗粒加入导致熔体粘度增加、颗粒堵塞枝晶间的补缩流动通道以及颗粒与基体合金的热膨胀系数的差异三种因素所引起；第二种材料由于气孔易在ＳｉＣ颗粒表面形核，或者ＳｉＣ颗粒与基体结合较弱，使得该复合材料比前者易形成显微孔隙；第三种复合材料，是由于ＳｉＯ２颗粒与基体间发生了界面反应，一定量的Ｓｉ溶入了基体，增大了基体的凝固潜热，从而提高了基体合金凝固时的补缩流动能力，所以ＳｉＯ２ｐ／Ａｌ－４％Ｍｇ复合材料的凝固组织比同样条件下Ａｌ２Ｏ３ｐ／Ａｌ－４％Ｍｇ和ＳｉＣｐ／Ａｌ－４％Ｍｇ复合材料致密。     

微量Sc和Zr对Al—Mg合金铸态组织的晶粒细化作用

制备了Ａｌ５Ｍｇ、Ａｌ５Ｍｇ０．２Ｓｃ、Ａｌ５Ｍｇ０．１Ｚｒ和Ａｌ５Ｍｇ０．２Ｓｃ０．１Ｚｒ四种铸态合金，采用金相显微镜和扫描电镜观察分析了微量Ｓｃ和Ｚｒ对ＡｌＭｇ合金铸态组织的晶粒细化作用及其机理。结果发现，０２％的Ｓｃ并未使ＡｌＭｇ合金产生晶粒细化作用，而０２％的Ｓｃ与０１％的Ｚｒ复合添加则使ＡｌＭｇ合金产生了极其强烈的晶粒细化作用。这一作用的产生，是由于Ｓｃ、Ｚｒ与Ａｌ在合金熔体中生成了Ａｌ３Ｓｃ和Ａｌ３Ｚｒ复合粒子，这种粒子在合金凝固过程中，起到了非均质晶核细化晶粒的作用     

Stirring brazing of dissimilar Al/Mg alloy without flux in air

AZ31B magnesium alloy and 2024 aluminum alloy were successfully jointed at aid of mechanical stirring with Sn-Zn-Al filler metal. The microstructure, fracture morphologies, and mechanical properties of joint were investigated. The results show that Mg-Al intermetallic compounds can be avoided by the process. But, a small quantity of porosity is found in the joint. The sheafing strength of joint interface adjacent to magnesium alloy is 35.4 MPa for formation of Mg-Sn intermetallic compounds, which is about 46 % of that of filler metal. While, the shearing strength of joint interfaces adjacent to aluminum alloy is 70.4 MPa for formation of Zn-Sn-Al solid solution, which is about 92 % of that of filler metal.     

Effects of Sn and Ca additions on microstructure,mechanical properties,and corrosion resistance of the as‐cast Mg‐Zn‐Al‐based alloy

Effects of Sn and Ca additions on microstructure, mechanical properties, and corrosion resistance of the as‐cast Mg‐6Zn‐2Al‐based alloy were investigated by SEM, XRD, tensile tests, electrochemical measurements, etc. The higher the Sn content, the higher the yield strength of the Mg‐6Zn‐2Al‐based alloy. Trace Ca addition refined both grains and divorced eutectics in the Mg‐Zn‐Sn‐Al alloys, leading to the best combination of strength and plasticity. Moreover, its influence was more significant for the alloy with a higher Sn content. Furthermore, the combined addition had a beneficial effect on the corrosion resistance improvement of the Mg‐6Zn‐2Al alloy. The Mg‐6Zn‐2Al‐3Sn‐0.2Ca alloy was the most corrosion‐resistant alloy among the nine alloys studied, better than AZ91 and ZA85. It could be ascribed to the decrease and the refinement of divorced eutectics, the higher hydrogen overvoltage of Sn and the Ca grain refinement.     

Microstructural characterisation and mechanical properties of Mg–xSn–5Al–1Zn alloys

Abstract

In this study, the microstructure and mechanical properties of as cast Mg–x Sn–5Al–1Zn alloys were investigated. The microstructures of the alloys were characterised by the presence of Mg₂Sn and Mg₁₇Al₁₂ precipitates. The greatest tensile strength and elongation were obtained at the alloy containing 5 wt-%Sn at room temperature. Microhardness of the alloys and volume fraction of the Mg₂Sn precipitates increased with increasing Sn content. Fractographic analysis demonstrated that dimple and cleavage facet were dominant mechanisms of these alloys tested at room and elevated temperature. The portion of cleavage facet was increased with the increment of Sn at the room and elevated temperatures.     

Microstructure and mechanical properties on aging behavior of Zn containing Mg–2Sn–0.4Mn alloy

The effects of Zn addition were examined by observing the microstructure and measuring the mechanical properties of Mg–xZn–2Sn–0.4Mn with different Zn contents. The addition of Zn to the Mg–2Sn–0.4Mn alloy caused the precipitation of secondary phases and an improvement in the mechanical properties. The aged alloys showed improved elongation at break, which led to a slight decrease in yield strength and ultimate strength. The results suggest that the formation of precipitates containing Zn affects the mechanical properties of the alloys.     

TENSILE PROPERTIES AND CREEP RESISTANCE OF AZ91 ALLOY CONTAINING ANTIMONY

1.IntroductionMagnesiumalloysarebeingincreasinglyilsedinmanymanufacturingindustries,espe-ciallyintheautomobileindustryinordertosaveweighttherebyreducingfuelconsumptionandpollution.AlloyAZ91(Mg-9Al-o.8Zn-O.2Mn)withexcellentcastabilityandcorrosionresistanceisthemostfavoredmagnesiumalloy,beingusedinapproximately9O%ofallmagnesiumcastproducts[1].However,therangeofapplicationsforthisalloyislimitedbytheirlowstrengthandpoorcreepresistanceatthetemperaturesabove12Owr,whichmakesitunsuitableformanyofc…     

Microstructure and mechanical properties of ZA62 based magnesium alloys with calcium addition

As-cast microstructure and mechanical properties of Mg-6Zn-2Al-0.3Mn (ZA62) alloys with calcium addition were investigated.The as-cast microstructure of the base alloy ZA62 consists of the α-Mg matrix and eutectic phase Mg51Zn20.The Mg51Zn20 eutectic was gradually replaced by MgZn phase and Mg32(Al,Zn)49 phase when calcium is added into the base alloy.Further addition of calcium leads to the increase of grain boundary phases and formation of a new quaternary Mg-Zn-Al-Ca eutectic compound.In comparison with the base alloy,the increase of calcium addition to the base alloy results in the reduction of both strength and ductility at ambient temperature,but increase at elevated temperatures due to the thermal stability of Ca-containing phases.At elevated temperatures,the creep resistance of ZA62 based alloys containing calcium is significantly higher than that of AZ91 which is the most commonly used magnesium alloy.     

Effect of Cu addition on microstructure and properties of Mg-10Zn-5Al-0.1Sb high zinc magnesium alloy

To improve the strength,hardness and heat resistance of Mg-Zn based alloys,the effects of Cu addition on the as-cast microstructure and mechanical properties of Mg-10Zn-5Al-0.1Sb high zinc magnesium alloy were investigated by means of Brinell hardness measurement,scanning electron microscopy (SEM),energy dispersive spectroscopy (EDS),XRD and tensile tests at room and elevated temperatures.The results show that the microstructure of as-cast Mg-10Zn-5Al-0.1Sb alloy is composed of α-Mg,t-Mg32(Al,Zn)49,φ-Al2Mg5Zn2 and Mg3Sb2 phases.The morphologies of these phases in the Cu-containing alloys change from semi-continuous long strip to black herringbone as well as particle-like shapes with increasing Cu content.When the addition of Cu is over 1.0wt.%,the formation of a new thermally-stable Mg2Cu phase can be observed.The Brinell hardness,room temperature and elevated temperature strengths firstly increase and then decrease as the Cu content increases.Among the Cu-containing alloys,the alloy with the addition of 2.0wt.% Cu exhibits the optimum mechanical properties.Its hardness and strengths at room and elevated temperatures are 79.35 HB,190MPa and 160MPa,which are increased by 9.65%,21.1% and 14.3%,respectively compared with those of the Cu-free one.After T6 heat treatment,the strengths at room and elevated temperatures are improved by 20% and 10%,respectively compared with those of the as-cast alloy.This research results provide a new way for strengthening of magnesium alloys at room and elevated temperatures,and a method of producing thermally-stable Mg-10Zn-5Al based high zinc magnesium alloys.     

微量Sr、Sn对Mg-Zn-Ca-Mn合金力学和腐蚀性能的影响

目的研究Sr、Sn元素对快速凝固制备的Mg ZnCaMn合金室温力学性能和生物腐蚀性能的影响规律。方法采用X射线衍射仪、扫描电子显微镜、差热分析仪、万能力学实验机、静态浸泡、电化学测试等实验手段,分别研究添加Sr/Sn元素对MgZnCaMn合金结构、微观组织变化、热学性能、室温强度、塑性变形及体外降解行为的影响。结果添加Sr元素后,MgZnCaMn合金中的非晶相数量增加,尤其是Mg64.7Zn30Ca4Mn0.8Sr0.5合金浸泡析氢量显著降低,自腐蚀电流密度为1.61×10~(-4)A/cm~2,平均腐蚀速率为0.35 mm/a,抗压强度为621MPa,塑性压缩应变为0.8%。添加Sn元素后,MgZnCaMn合金中的非晶相近乎完全消失,合金组织中主要为雪花状的Mg2Sn相及MnZn13相,合金的析氢量无显著变化,其与Mg65.2Zn30Ca4Mn0.8合金的自腐蚀电流密度皆在10~(-4)数量级,其抗压强度为412 MPa,压缩塑性应变为1.6%。结论添加Sr元素可以提高MgZnCaMn合金的非晶形成能力,增加非晶相体积分数,同时提升了合金的强度和腐蚀性能。添加Sn元素则降低了MgZnCaMn合金的非晶形成能力,合金主要由延性相构成,其室温塑性得到明显改善,与初始合金相比,耐蚀性略有降低,但仍然优于常规的生物医用镁合金(如高纯镁、Mg-Zn-Ca等),具有较好的耐蚀性。     

Mg-Al-Sn钎料及其AZ61A镁合金钎焊接头组织性能分析

采用扫描电镜、X射线衍射分析、热分析等手段分析了Mg58.5Al31.5Sn10和Mg58.5Al31.5Sn10RE两种钎料及其钎焊AZ61A镁合金对接接头组织性能. 结果表明,Mg58.5Al31.5Sn10钎料及其钎缝组织主要由块状Mg2Sn和(Mg17Al12+Mg2Sn)二元共晶相组成,并含有少量三元共晶相(Mg17Al12+Mg2Sn+α-Mg). Mg58.5Al31.5Sn10RE钎料及其钎缝组织中未发现块状Mg2Sn相,其组织主要由(Mg17Al12+Mg2Sn+α-Mg)三元共晶和(Mg17Al12+Mg2Sn)二元共晶相及少量Al-RE组成. 和Mg58.5Al31.5Sn10钎料相比,Mg58.5Al31.5Sn10RE组织更加均匀细小,固液相线温度明显降低,熔程缩短了6 ℃,铺展面积提高了5.4%,对接接头平均抗拉强度提高了8.6%,二者拉伸断口形貌均呈现为脆性断裂.