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。     

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 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.     

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.     

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。     

Corrosion mechanism and corrosion model of Mg-Y alloy in NaCl solution

Corrosion of Mg–Y alloy was studied using electrochemical evaluations, immersion tests and SEM observations. Corrosion mechanisms of Mg-(0.25 and 2.5) Y alloy and Mg-(5, 8, and 15) Y alloy were uniform corrosion and pitting corrosion respectively, and the content of Mg_(24)Y_5 phases determined its effect acting as cathode to accelerate the corrosion or corrosion barrier to inhibit the corrosion. Corrosion resistance of Mg-(0.25, 2.5, 5, 8, and 15) Y alloys was as follows: Rt(Mg-0.25Y) Rt(Mg-8Y) Rt(Mg-15Y) Rt(Mg-5Y) Rt(Mg-2.5Y). Y could significantly improve the corrosion resistance of the Mg-Y alloy, but the excess of Y deteriorated the corrosion resistance of the Mg-Y alloy. The optimum content of Y in the studied alloys was 2.5%.     

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。     

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.     

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.     

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.     

Si和Ca对铸态Mg-5Sn-0.5Sr合金组织和性能的影响

为了提高镁合金的耐热性能,在Mg-5Sn-0.5Sr合金中加入Si和Ca等合金化元素,设计了Mg-5Sn-0.5Sr-xSi(x=1,2)和Mg-5Sn-0.5Sr-xSi-0.5Ca(x=1,2)合金.采用x-射线衍射仪(XRD)、光学显微镜(OM)与扫描电镜(SEM)研究了合金的相组成及显微组织,并利用力学性能试验机测定了合金的拉伸性能.结果表明,Mg-5Sn-0.5Sr-xSi(x=1,2)合金组织由沿α-Mg晶界析出的共晶Mg₂Sn、Mg₂Si相与α-Mg晶内初生MgSnSr相组成,且Mg₂Si相的质量分数随Si元素的增加而增加.对于Mg-5Sn-0.5Sr-xSi-0.5Ca(x=1,2)合金而言,加入Ca元素能够显著促进初生(Ca,Sr)MgSn相的形成,而抑制晶界上Mg₂Sn相的析出.     

Al-6Zn-2Mg-2Cu合金热处理后的拉伸与晶间腐蚀性能

为了研究不同时效处理对Al-6Zn-2Mg-2Cu合金性能的影响,研究了强化固溶后T6和T76时效处理对Al-6Zn-2M g-2Cu合金硬度、拉伸性能与晶间腐蚀性能的影响.结果表明,强化固溶后与经过T6时效处理的合金相比,T76时效处理后合金的硬度并无明显变化,但合金的抗拉强度下降了4.39%,伸长率则明显上升.经T6和T76时效处理后,合金的晶间腐蚀等级均为4级.两种时效状态下合金腐蚀速率均在0~1.5 h范围内急剧增大,之后开始下降.经过强化固溶与T76时效处理后,合金的抗晶间腐蚀性能得到明显改善.     

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...     

Microstructure characterization and electrochemical corrosion behavior of Zn and Zn/Mg alloys in H_2SO_4 solution

The three systems of pure Zn, Zn-0.10% Mg(mass fraction), and Zn-0.15% Mg(mass fraction) were cast under controlled atmosphere and their microstructures were characterized by SEM/EDS analysis. The electrochemical corrosion behavior of these three samples was examined in the very aggressive solution of 50% H2SO4(mass fraction) using electrochemical impedance spectroscopy(EIS) and potentiodynamic polarization measurements. The results show that magnesium improves in some extent the corrosion resistance of pure Zn in 50% H2SO4(mass fraction) confirmed by EIS test. Results of polarization measurment also demonstrate that small amount of Mg significantly improves the passivation of Zn in the test solution. Results of surface morphology of the samples and EDS analysis reveal that Mg reduced the corrosion attacks to pure Zn.     

Corrosion Behavior of Mg65Cu25-xZnxGd10 (x=0, 5) Metallic Glass

The effect of substitutional element Zn on corrosion behavior of Mg65Cu25Gd10 glass was investigated. The amorphous structure of Mg65Cu25-xZnxGd10(x=0, 5) alloys were examined by X-ray diffractometry and differential scanning calorimetry (DSC). The dissolution rates of Mg65Cu25-xZnxGd10(x=0,5) metallic glasses in a 5 wt% NaCl solution with pH value of 7 were determined by a hydrogen evolution testing method. The corrosion behavior of these alloys was characterized using dipping tests with 5 wt% NaCl, in combination with electrochemical measurements and scanning electron microscopy (SEM). Results show that the anti-corrosion ability of Mg65Cu25Gd10 alloy is significantly improved due to the addition of Zn. Possible mechanism responsible for the improvement is discussed.     

Sr对Mg-5Sn-5Zn铸造镁合金组织的影响

通过光学显微镜、扫描电镜和X射线衍射仪研究了Mg-5Sn-5Zn-xSr（x=0,0.5,1,2）4种铸造镁合金的显微组织和相组成.结果表明：在Mg-5Sn-5Zn合金中加入质量分数为0.5%～2%的Sr元素后,不但能够缩小α-Mg枝晶间距,而且还能形成三元相MgSnSr.随着Sr含量的增加,在晶界析出的Mg2Sn相减少,晶内的MgSnSr相增加。合金中的MgZn相与Mg2Sn相依附在一起,大多数的MgZn相以α-Mg＋MgZn相的共晶方式存在.     

Sn对AX55铸造合金组织与蠕变性能的影响

为了提高Mg-5Al-5Ca(AX55)铸造镁合金基体组织和共晶组织的耐热性能,以Sn为变量设计了AX55-x Sn(x=0,0. 5,1. 0,1. 5)合金,研究了T61和T62对合金组织、硬度与蠕变性能的影响.结果表明,随着Sn含量的增加,合金基体中析出的Al2Ca相增多,使得α-M g基体得到强化.在共晶骨架相附近析出的CaMgSn相可使共晶组织得到强化.在175℃/70 MPa蠕变100 h条件下,AX55-x Sn合金的最小蠕变速率和蠕变总量随Sn含量的提高而降低. AX55-1. 5Sn合金性能最佳,且其最小蠕变速率为5. 21×10-8s-1,100 h总蠕变量为0. 065%.相比T61,T62能够提高AX55-x Sn合金的基体硬度和蠕变性能.     

喷射沉积含Sc超高强铝合金固溶处理组织与性能分析

采用金相、扫描电镜、X射线衍射分析方法,研究了不同工艺条件下喷射沉积Al-12Zn-2.4Mg-1.1Cu-0.20Zr-0.30Sc-0.30Ni合金的微观组织与力学性能.结果表明,过喷粉颗粒的大小为3~15μm,是沉积坯等轴晶平均直径的1/6~3/4;挤压坯经460℃/0.5 h+480℃/2 h二级固溶处理后Zn,Mg,Cu等溶质元素回溶到Al基体中,固溶后未见形成W(ScCu6.6~4Al5.4~8)相,合金抗拉强度由挤压态的410 MPa增加到固溶态的750 MPa,增幅为82.9%;再经T6时效后合金的抗拉强度可达855 MPa.凝固过程形成的粗大难溶DO23结构Al3(Sc,Zr)粒子是影响合金抗拉强度的重要原因.     

时效态Al-Zn-Mg-Cu-Zr-Sc合金的组织与疲劳性能

为了研究时效处理对Al-7.2Zn-2.5Mg-1.5Cu-0.08Zr-0.12Sc合金的组织与疲劳性能的影响,利用透射电子显微镜对合金的显微组织进行了观察分析,并针对不同时效状态的合金进行了低周疲劳实验.结果表明,经过150℃×6 h时效处理后,合金晶内析出相较少,晶界无析出相;经过150℃×36 h时效处理后,合金晶内析出相较为细小,并呈弥散分布,同时晶界析出断续分布的平衡相,并存在晶界无析出带;经过150℃×48 h时效处理后,合金的析出相均已长大,且晶界无析出带发生宽化.经过150℃×36 h时效处理后的合金,表现出了较高的循环变形抗力与较长的低周疲劳寿命;不同时效状态合金的塑性应变幅、弹性应变幅与载荷反向周次之间,以及循环应力幅与塑性应变幅之间均呈线性关系.     

Mg-4Zn-0.5Y-0.5Nd-0.3Zr镁合金动态压缩行为及变形组织

为了研究挤压态Mg-4Zn-0.5Y-0.5Nd-0.3Zr镁合金在高应变速率下的动态压缩失效行为及组织演变规律,采用分离式霍普金森压杆装置进行了动态压缩实验,并采用光学显微镜对压缩后镁合金的组织演变规律进行了研究.结果表明,在不同应变速率下挤压态Mg-4Zn-0.5Y-0.5Nd-0.3Zr镁合金呈现出相似的屈服现象,并表现为正应变率强化效应.在较低的应变速率下,平行于加载方向的小裂纹的形成、晶粒长大和孪生均可消耗冲击能量.在较高的应变速率下,试样内部的塑性变形能力得到提高且发生了加工硬化现象,而试样边缘萌生了裂纹.