Effect of Homogenization Treatment on the Corrosion Behavior and Mechanism of Mg-Y Alloys

The effect of homogenization treatment on the corrosion behavior and corrosion mechanism of Mg-Y alloys in 3.5 wt% NaCl solution was investigated by electrochemical characterization,immersion testing and SEM observations.The diffusion kinetics model of Mg-Y alloy was established,and the homogenization system was determined.With increasing of homogenization temperature and time,the Mg_(24)Y_5 phase gradually decreased,which increased the self-corrosion potential and the high-frequency arc radius.The corrosion resistance of the five alloys could be given as follow:Mg-0.25Y Mg-8Y Mg-15Y Mg-5Y Mg-2.5Y.The Mg-(0.25,2.5 and 5) Y show localized corrosion in a wide range and small depth,while Mg-(8 and 15) Y showed localized corrosion in a smaller range and larger depth.     

Influence of Nd and Y additions on the corrosion behaviour of extruded Mg-Zn-Zr alloys

To improve the corrosion resistance of wrought magnesium alloys through rare earth (RE) additions, the corrosion behaviour of Mg-5Zn-0.3Zr-xNd (x=0, 1, and 2; wt%) and Mg-5Zn-0.3Zr-2Nd-yY (y=0.5 and 1; wt%) alloys in a 5wt% NaCl solution was investigated using immersion test and electrochemical measurements. The results of immersion test show that Mg-5Zn-0.3Zr-2Nd alloy exhibits the best corrosion resistance among the tested alloys. Electrochemical measurements show that secondary phases in RE-containing Mg...     

Electrochemical behavior of Mg-Al-Pb alloy in 3.5% NaCl solution

An investigation on electrochemical behavior of Mg-5%Pb alloy, Mg-6%Al alloy and Mg-6%Al-5%Pb alloy(mass fraction) in 3.5% Na Cl(mass fraction) solution was conducted using electrochemical measurements and corroded morphology observation, in which solid solution and the as-aged state of each alloy were compared to discuss the influence mechanism of lead and aluminium on the electrochemical properties of alloys. The X-ray diffraction(XRD) analysis was performed to make microstructure characterization. The electrochemical results indicate that the corrosion of Mg-5%Pb alloy is predominated by homogeneous pitting and dissolution of PbCl_2 film due to Cl ions attack, while corrosion crevice propagates along grain boundaries in solid solution of Mg-6%Al alloy and the micro galvanic corrosion also plays vital role in Mg_(17)Al_(12) phase containing experimental alloys. The co-existence of lead and aluminium in magnesium alloy increases corrosion current density and electrochemical activity as well. The comparison between solid solution and the as-aged state demonstrates that Mg_2 Pb and Mg_(17)Al_(12) somewhat increase corrosion resistance but lighten anodic polarization by facilitating corrosion product flaking off.     

镁锰钙合金在模拟人体体液中的腐蚀行为研究

通过添加锰（Mn）的方法来提高镁（Mg）合金在模拟人体体液（Hanks模拟体液）环境中的耐腐蚀性。采用熔剂覆盖法炼制了Mg-xMn-0.5Ca（x=0.5;1.0;2.0）合金;实验结果表明,在Hanks模拟体液中浸泡4 d后,Mg-1Mn-0.5Ca合金腐蚀程度最低;交流阻抗谱测试表明,三者交流阻抗谱都由单一容抗弧线组成,浸泡4 d后,Mg-1Mn-0.5Ca合金的容抗弧半径最大,说明三种成分的镁合金以Mg-1Mn-0.5Ca合金的耐蚀性最佳。     

Mg-Zn-Ca合金中Zn对腐蚀性能的影响

采用熔剂保护法制备了3种Zn含量分别为0.5%,1%和2%的Mg-Zn-Ca合金,其在Hank’s模拟体液中进行了浸泡腐蚀实验及电化学实验测试。实验结果表明：在Hank’s模拟体液中,含锌量为0.5%镁合金腐蚀速率最小且自腐蚀电位最高;三种成分镁合金的交流阻抗谱以含锌量为0.5%镁合金的容抗弧最大,说明含锌量为0.5%的镁合金耐腐蚀性能最佳。     

稀土Gd对Mg-5Al系镁合金显微组织与疲劳性能的影响

为了确定稀土元素Gd和时效处理对Mg-5Al系压铸镁合金显微组织及疲劳性能的影响,通过低周疲劳实验对压铸态和时效态Mg-5Al-x Gd镁合金的显微组织和疲劳性能进行了表征.结果表明,提高压铸态和时效态Mg-5Al-x Gd镁合金中Gd的含量,可使镁合金的显微组织得到细化.在总应变幅控制的低周疲劳加载条件下,压铸态和时效态Mg-5Al-x Gd镁合金均呈现出循环硬化和循环稳定特征,时效处理可以提高Mg-5Al-x Gd压铸镁合金的循环变形抗力.对于压铸态镁合金而言,Gd含量为1%时镁合金的循环变形抗力高于Gd含量为2%和3%的镁合金,而对于时效态镁合金而言,Gd含量为1%和2%时镁合金的循环变形抗力均高于Gd含量为3%的镁合金.     

Ca对医用Mg-1Zn-xCa合金材料在模拟体液中腐蚀行为的研究

Mg-1Zn-xCa（x=0.25,0.5,1）合金通过浸泡于模拟体液（Hank’s模拟体液）中在恒温（37℃）条件下进行为期0～32 d的腐蚀浸泡实验.对浸泡后的试样宏观腐蚀形貌观察,测定其腐蚀速率.在浸泡期间测其交流阻抗和极化曲线,研究Ca含量对镁合金组织和腐蚀性能的影响。实验结果表明：在Hank’s模拟体液中,随着含Ca量的增加（x=0.25%,0.5%,1%）,Mg-2Zn-xCa合金的腐蚀程度加剧,腐蚀速率增大;由交流阻抗谱和极化曲线的测试分析发现,随着含Ca量的增加,交流阻抗谱的容抗弧逐渐增大,极化电流密度逐渐减小,镁合金的耐蚀性逐渐降低;因而,三种镁合金中Mg-1Zn-0.25Ca合金表现出最佳的抗腐蚀性能。     

Microstructures, mechanical properties and compressive creep behaviors of as-cast Mg-5%Sn-（0-1 .0）%Pb alloys

The microstructures, tensile properties and compressive creep behaviors of Mg-5%Sn-(0–1.0)%Pb (mass fraction) alloys were studied. The microstructures of the Mg-Sn-Pb alloys consist of dendritic α-Mg and Mg₂Sn phase. The addition of Pb can refine the size of Mg₂Sn phase and grain size, reduce the amount of Mg₂Sn phase at grain or inter-dendrite boundaries and change the distribution of Mg₂Sn phase. Pb exists in the Mg₂Sn phase or dissolves in α-Mg matrix. The mechanical properties of the tested alloys at room temperature are improved with the addition of Pb. When the Pb content is over 0.5%, the mechanical properties are decreased gradually. The Mg-5%Sn-0.5%Pb shows the best ultimate tensile strength and elongation, 174 MPa and 14.3%, respectively. However, the compressive creep resistance of the Mg-Sn-Pb alloys is much lower than that of the Mg-Sn binary alloy at 175 °C with applied load of 55 MPa, which means that Pb has negative effects on the compressive creep resistance of the as-cast Mg-Sn alloys.     

Effects of Y Content on the Microstructures and Mechanical Properties of Mg-5Zn-xY-0.6Zr Alloys

Three as-cast and as-extruded Mg-5Zn-x Y-0.6Zr(x=5 wt%, 8 wt%, 11 wt%) alloys were prepared, and the effects of Y content on the microstructures and mechanical properties of the alloys were investigated. The results show that the investigated Mg-Zn-Y-Zr alloys mainly consist of a-Mg, X-Mg12 YZn and minor amount of W-Mg_3Y_2Zn_3 phases. The volume fraction of X-Mg_(12) YZn phase increases and that of W-Mg_3Y_2Zn_3 phase decreases with the rising of Y content in the alloys. The as-extruded Mg-5Zn-11Y-0.6Zr alloy owns the optimal ultimate tensile strength and yield strength of 429 and 351 MPa, respectively. Mg-5Zn-5Y-0.6Zr alloy owns the maximum elongation of 13.6%.     

Effect of homogenization treatment on microstrucmre and properties of Al-Mg-Mn-Sc-Zr alloy

The effect of homogenization on the hardness, tensile properties, electrical conductivity and microstructure of as-cast Al-6Mg-0.4Mn-0.25Sc-0.12Zr alloy was studied. The results show that during homogenization as-cast studied alloy has obviously hardening effect that is similar to aging hardening behavior in traditional Al alloys. The precipitates are mainly Al3（Sc,Zr） and Al6Mn When homogenization temperature increases the hardness peak value is declined and the time corresponding to hardness peak value is shortened. The electrical conductivity of the alloy monotonously increases with increasing homogenization temperature and time. The decomposition of the supersaturated solid solution containing Sc and Zr which is formed during direct chilling casting and the precipitation of Al3（Sc, Zr） cause hardness increasing. The depletion of the matrix solid solubility decreases the ability of electron scattering in the alloy, resulting in the electrical conductivity increased. Tensile property result at hot rolling state shows that the optimal homogenization treatment processing is holding at 300-350℃ for 6-8 h.     

三种Mg—Gd—Y系合金显微组织分析

为了进-步研究不同热处理状态对Mg-Gd-Y系合金显微组织的影响,采用光学显微镜（（）M）、透射电子显微镜（TEM）和X射线衍射仪（XRD）分析了Mg-20Gd、Mg-20Y和Mg-9Gd-3Y合金恒温处理前后的微观组织与相组成．研究结果表明：Mg-20Gd、Mg-20Y和Mg-9Gd-3Y合金在室温的平衡态显微组织分别是0t-Mg＋GdMg5、0t-Mg＋Mg24Y5和a-Mg＋GdMg5＋Mg24Y5;实验合金在520℃8h＋300。C144h恒温处理后,Mg-20Gd合金中有平衡相GdMgs和非平衡相Mg3Gd,其中析出相为MgGds;Mg-20Y合金中有平衡相Mg2aYs,其中析出相是Mgz-Ys;Mg-9Gd-3Y合金中有平衡相GdMg5、Mg24Y5和非平衡相Mg2Gd,析出相为GdMg5与Mg24Y5．     

Effect of low temperature aging on microstructure and mechanical properties of super-high strength aluminum alloy

The effects of heat treatment on the microstructure and mechanical properties of two alloys, namely Al- 12.2%Zn-2.48%Cu-2.0%Mg-0.15%Zr-0. 166%Ag（alloy 1）, and Al-9.99%Zn-1.72%Cu-2.5%Mg-0.13%Zr（alloy 2） were investigated. The results show that low temperature aging after promotive solution treatment can increase elongation without the loss of strength for the studied alloys. The optimum aging treatment （T6） for alloy 1 and alloy 2 is 100 ℃/80 h and 100 ℃/48 h, respectively. Compared with other heat treatment alloys, alloy 1 and alloy 2 show super-high tensile strength up to 753 MPa and 788 MPa, remaining 9.3% and 9.7% elongation under T6 condition, respectively. During aging, trace addition of Ag enhances the formations of GP zone and metastable phase, and stabilizes GP zone and metastable phase to a higher temperature. Trace addition of Ag prolongs the aging time of reaching the peak strength and delays over-aging condition of the alloy. However, trace addition of Ag promotes the formation of coarse constituent in the alloy and consumes hardening alloying elements of Zn and Mg. Moreover, the addition of the transition element Zr in 7000 series super-high alloy forms incoherent Al3 Zr dispersoid which can serve as nucleation sites for nonuniform precipitation of η phase during aging process. The higher the aging temperature, the greater the tendency for nonuniform precipitation of η phase.     

涂敷Na2SO4盐膜的Ni基合金在900℃空气中的热腐蚀

采用涂盐法,在纯Ni、Ni-10Cr、Ni-20Cr和Ni-10Cr-5Al合金上涂敷40～ 45 g/m2厚度Na2SO4盐膜,研究其在900℃空气中的热腐蚀行为.结果表明：纯Ni和3种Ni基合金的抗热腐蚀性能依纯Ni、Ni-10Cr-5Al、Ni-10Cr、Ni-20Cr的次序递增.3种Ni基合金形成了相似的腐蚀膜结构,腐蚀膜大体分3层,外层都是NiO.Ni-20Cr合金中间层为连续的Cr2O3层,内部出现极少的硫化物;Ni-10Cr合金腐蚀膜的中间层是相对深色的NiO和Cr2O3混合层,内侧出现硫化物;而Ni-10Cr-5Al合金腐蚀膜的中间层是NiO、Cr2 O3和Al2O3的混合氧化物,内层是Cr和Al的硫化物,分布在腐蚀膜和基体的界面上,有的分布在合金基体上.在Ni的基础上添加Cr并增加Cr含量均提高了合金的抗热腐蚀性能,但在Ni-10Cr的基础上增加质量分数5％Al却使抗热腐蚀性能下降.     

Ca对Mg-6Al-1Nd合金显微组织和性能的影响

为了研究Ca元素对Mg-6Al-1Nd合金微观组织、力学性能和阻燃性能的影响规律,采用了金属型重力铸造方法制备了Mg-6Al-1Nd-x Ca合金.通过金相显微镜、扫描电镜、万能拉伸试验机和热分析仪等分析测试手段对Mg-6Al-1Nd-x Ca合金的显微组织、力学性能和阻燃性能进行了表征.结果表明:Ca元素的加入可减少β-Mg17Al12含量,生成Al-Ca金属间相;随着Ca质量分数的增加,镁合金试样中的Al-Ca金属相增多,试样的室温抗拉强度和延伸率降低,阻燃性能升高;不含Ca元素的Mg-6Al-1Nd合金的抗拉强度为235 MPa,当Ca元素增加到2.5%时,Mg-6Al-1Nd-2.5Ca合金的抗拉强度仅为154 MPa,但该合金的着火点可达850℃.     

Microstructure and mechanical properties of Al-Zn-Cu-Mg-Sc-Zr alloy after retrogression and re-aging treatments

The mechanical properties and stress corrosion cracking (SCC) resistance of an Al-Zn-Cu-Mg-Sc-Zr alloy under different aging conditions were investigated. The dependence of microstructure and mechanical properties on aging parameters was evaluated by tensile test, hardness test and conductivity measurement. The results show that for the alloys with retrogression and re-aging treatment (RRA), the conductivity increases with the retrogression time and temperature, while the tensile strength decreases. The transmission electron microscopy (TEM) results show that the precipitates η(MgZn₂) at grain boundary aggregate apparently with retrogression time and the precipitates inside the matrix exhibit the similar distribution to T6 temper, which comprises fine GP zones, large η′(MgZn₂) and η(MgZn₂) phases. According to the mechanical properties and microstructure observations, the optimal RRA regime is recommended to be 120 °C, 24 h + 180 °C, 30 min + 120 °C, 24 h. The strength level of the alloy after the optimum RRA treatment is similar to that in T6 condition and the SCC resistance is improved obviously in contrast to T6 condition.     

Microstructure, cold rolling, heat treatment, and mechanical properties of Mg-Li alloys

The magnesium-lithium (Mg-Li) alloy exhibits two phase structures between 5.7wt% and 10.3wt% Li contents, consisting of the α (hcp) Mg-rich and the β (bcc) Li-rich phases, at room temperature. In the experiment, Mg-5Li-2Zn, Mg-9Li-2Zn, Mg-16Li-2Zn, Mg-22Li-2Zn, Mg-5Li-2Zn-2Ca, Mg-9Li-2Zn-2Ca, Mg-16Li-2Zn-2Ca, and Mg-22Li-2Zn-2Ca (wt%) were melted. During the melting process, the flux, which was composed of lithium chloride (LiCl) and lithium fluoride (LiF) in the proportion of 3:1 (mass ratio) and argon gas were used to protect the alloys from oxidation. The microstructure, mechanical properties, and cold-rolling workability of the wrought alloys were studied. The crystal grain of the alloys (adding Ga) is fine. The hardness of the studied alloys decreases with an increase in element Li. The density of the studied alloys is in the range of 1.187 to 1.617 g/cm3. The reduction of the Mg-16Li-2Zn and Mg-22Li-2Zn alloys can exceed 85% at room temperature. The Mg-9Li-2Zn-2Ca alloy was heat treated at 300°C for 8, 12, 16, and 24 h, respectively. The optimum heat treatment of the Mg-9Li-2Zn-2Ca alloy is 300°C×12h by metallographic observation and by studying the mechanical properties of the alloys.     

Effect of heat treatment on microstructures and mechanical properties of Al-6Zn-2Mg-1.5Cu-0.4Er alloy

The microstructures and mechanical properties of A1-6Zn-2Mg-1.5Cu-0.4Er alloy under different treatment conditions were investigated by transmission electron microscopy (TEM) observation, and tensile properties and hardness test, respectively. The relationship between mechanical properties and microstructures of the alloys was discussed. With trace Er addition to A1-Zn-Mg-Cu alloy, Er and Al interact to form Al3Er phase, which is coherent with α(Al) matrix. The results show that A1-Zn-Mg-Cu alloy after retr...     

Zn、Y对普通凝固Mg-Zn-Y合金组织性能的影响

为了获得一种高质量的含有二十面体准晶相的准晶合金,采用金属型铸造方法制备了Mg-Zn-Y合金.利用扫描电子显微镜、能谱仪、X射线衍射仪和维氏硬度仪研究了Zn、Y元素对合金组织与性能的影响,并分析了准晶相的形成机制.结果表明,在普通凝固条件下准晶相可以直接在液相中形核并长大,合金硬度及准晶相的形貌、大小和分布与Zn、Y元素的含量密切相关.随着Zn含量的增加,Mg-x Zn-4.5Y合金硬度逐渐增大,组织中的准晶相由花瓣状向条状转变,且层片状共晶及α-Mg相逐渐消失.随着Y含量的增加,Mg-48Zn-y Y合金硬度逐渐增大,花瓣状准晶相数量逐渐增多,且层片状共晶组织变得更为致密.通过调节Zn、Y元素含量可以获得高质量准晶合金Mg-48Zn-13Y.     

Ga 对 Fe40Ni40P14B6 非晶合金电化学腐蚀行为的影响

具有高的玻璃形成能力Fe基非晶合金(Fe40Ni40P14B6)100-xGax(x=0,2.5和4.5)是利用单辊铜轮旋转的方法制备出来的.用电化学的方法研究非晶合金(Fe40Ni40P14B6)100-xGax(x=0,2.5和4.5)分别在1 mol/L和3 mol/L的HCl溶液中腐蚀行为,结果表明:非晶合金(Fe40Ni40P14B6)100-xGax(x=0,2.5和4.5)在HCl溶液中具有较高的腐蚀特性,并且随着Ga含量的增加,铁基非晶合金的耐腐蚀性能增加.另外,非晶合金(Fe40Ni40P14B6)100-xGax(x=0,2.5和4.5)与不锈钢(1Cr18Ni9Ti)分别在1 mol/L和3 mol/L的HCl溶液中的腐蚀行为相比,非晶合金的耐腐蚀性能更好.     

稀土在铝合金中的作用及研究进展

根据铝合金的传统分类方法,系统总结了稀土在铸造铝合金和变形铝合金中的作用,特别是在变形铝合金各个合金系中的作用. 作者发现,以往国内对稀土铝合金的研究主要集中在La、Ce、Y及混合稀土在铝及其合金中的作用和机理方面,对其他稀土元素在铝合金中的作用(诸如提高强韧性、耐蚀性及可焊性)研究甚少. 作者在稀土元素的选择上进行了深入研究,结果发现稀土Er在铝及其合金中具有显著作用,Er元素不仅能细化铝合金晶粒还能显著提高合金的强韧性、耐蚀性,因此有必要对其进行进一步研究.