Mg-5Zn-2Al-0.6Nd合金的部分重熔组织演变

利用光学显微镜、扫描电镜观察了Mg-5Zn-2Al-0.6Nd镁合金的铸态组织,分析了部分重熔温度对半固态非枝晶组织的影响.结果表明:Mg-5Zn-2Al合金中加入质量分数0.6%Nd后,铸态组织中出现呈针状或短棒状的稀土相.保温30min,部分重熔温度从585℃提高到610℃时,初生α-Mg相平均颗粒直径减小并且球化趋势更加明显.Mg-5Zn-2Al合金的部分重熔组织扩展经历了初始粗化,组织分离、球化和最后的粗化过程,加入0.6%Nd以后,部分重熔组织演变出现液化滞后现象,最后的粗化过程受到抑制.     

热浸Zn-Al-Mg和Zn-Al-Mg-Si合金镀层的组织与耐腐蚀性

对比研究热浸镀Zn-0.5Al-1.5Mg、Zn-2Al-1.5Mg和Zn-2Al-1.5Mg-0.3Si合金镀层组织与耐腐蚀性。用X射线衍射仪、扫描电子显微镜及能谱仪分析了合金镀层的组成相和显微组织,用全浸腐蚀试验和中性盐雾试验表征了合金镀层的耐腐蚀性能。结果表明:Zn-Al-Mg和Zn-Al-Mg-Si合金镀层主要由Zn相、Al相和Mg Zn2相组成;合金镀层主要含有Zn+Mg Zn2二元共晶组织和Zn+Al+Mg Zn2三元共晶组织;Al和Si有细化镀层晶粒作用,添加Si能提高Zn-Al-Mg-Si合金镀层的耐腐蚀性能。     

Mg-6Zn-(Al,Ca)镁合金显微组织及力学性能

利用WD-10A电子拉伸试验机和RD2-3型蠕变试验机对Mg-6Zn-(Al,Ca)系列镁合金的力学拉伸强度及高温蠕变性能进行测试,研究其显微组织对高温性能的影响,并利用金相显微镜、扫描电镜、X射线衍射分析等方法进行分析表征.研究结果表明,Mg-6Zn-2Al-0.3Mn(ZA62)具有较好的综合力学性能,其铸态显微组织主要由α-Mg基体和致密片状Mg51Zn20共晶相组成.少量Ca加入ZA62合金后,抑制了Mg51Zn20相的析出,并代之形成了含Ca的MgZn相和τ相.随Ca加入量增加,晶间相的数量增加,合金组织中出现另一热稳定四元Mg-Zn-Al-Ca化合物相.当w(Ca)>0.5%时,合金晶粒显著细化.随Ca含量增加,合金常温拉伸强度和塑性呈下降趋势,基体显微硬度减小.加入Ca提高了合金高温拉伸强度,改善了合金蠕变性能.在175℃/70 MPa条件下,合金蠕变性能受合金晶粒尺寸影响,随晶粒尺寸的减小,蠕变变形量增加.     

Al含量对AJC镁合金显微组织和力学性能的影响

以Mg-4Al-2Sr-1Ca合金为基体,在提高合金中Al含量的基础上,配制了不同成分的几种Mg-(4-7)Al-2Sr-1Ca合金.研究了Al含量对Mg-Al-Sr-Ca合金显微组织和力学性能的影响.研究发现,Mg-4Al-2Sr-1Ca合金的主要组成相为α-Mg,沿枝晶界分布的Mg2Ca α-Mg共晶相、Mg-Al-Sr三元相及晶内Al2Ca颗粒相.当Al元素质量分数增大到5%～6%时,合金中出现了(Mg,Al)2Ca相;进一步增大Al元素质量分数至7%,另一种新相Al4Sr相也被观察到.随着Al含量的增大,合金的强度和塑性在室温和高温下都有所上升.在175℃/70MPa和200℃/70MPa下,Mg-5Al-2Sr-1Ca和Mg-6Al-2Sr-1Ca合金表现出了比其他合金更好的高温抗蠕变性能.     

挤压对Mg-Zn-Sn-Al合金力学性能和腐蚀行为的影响

研究了铸态和挤压态Mg-4.5Zn-4.5Sn-2Al合金的微观组织、力学性能和在质量分数3.5%NaCl溶液中的腐蚀行为.结果表明:铸态合金的平均晶粒尺寸为183μm;而挤压后合金的平均晶粒尺寸降低为9μm.挤压态与铸态Mg-4.5Zn-4.5Sn-2Al合金相比,抗拉强度由209 MPa提高到354 MPa,屈服强度由157 MPa提高到216 MPa,伸长率达到19.6%且呈现明显的韧性断裂特征.静态浸泡腐蚀和电化学实验表明,挤压态合金的耐蚀性明显低于相应的铸态合金.     

Zr含量对医用Mg-5.5Zn-0.15Ca合金组织和性能的影响

在专用熔剂覆盖和氩气保护下制备Mg-5.5Zn-0.15Ca、Mg-5.5Zn-0.15Ca-0.5Zr、Mg-5.5ZnCa-0.6Zr、Mg5.5Zn-0.15Ca-0.7Zr、Mg-5.5Zn-0.15Ca-0.8Zr镁合金.采用光学显微镜、X射线衍射仪、室温力学测试设备对合金的显微组织与力学性能进行分析,研究Zr元素对热处理前后合金晶粒大小及铸态力学性能的影响.显微组织观察表明:Zr能显著地细化Mg-5.5Zn-0.15Ca合金的晶粒,随Zr元素含量的增加,合金的抗拉强度和伸长率均得到较大提高.     

Mg-Zn-Al系变形镁合金的显微组织和力学性能

制备了成分基于Mg-(3-5)Zn-(1-3)Al的5种ZA系镁合金,并研究了合金在铸态和热挤压态的显微组织和力学性能.在ZA系列的铸态镁合金中,将zn含量(质量分数)固定在3%,提高Al含量,则第2相由致密的共晶相ε(Mg51Zn20)变成呈典型的离异共晶形貌的T(Mg32(Al,Zn)49)相.在ZA31基础上增加Zn含量没有引起合金显微组织中组成相发生变化,但中间相ε的体积分数增加.在280 ℃温度下的热挤压过程中,合金发生了动态再结晶,组织显著细化,且铸态组织中出现的中间相大部分溶入α-Mg基体.ZA系合金铸锭热挤压后,合金的强度和塑性均得到大幅度改善,其中合金ZA51具有最好的强度和塑性的匹配.结果表明ZA系合金具有良好的热加工性能.     

Al含量对Zn—Al合金超塑性的影响

用恒载荷和恒夹头速度蠕为法研究了Zn－2．5Al、Zn－5Al和Zn－10Al合金的超塑性。研究表明，Zn－5Al共晶合金的超塑性优于亚共晶合金Zn-10Al及过共晶合金Zn－2．5Al，其优异的超塑性来源于细密的层片状共晶组织（α－β）。Zn－5Al合金的组织全部为（α＋β）共晶体，变形抗力低，晶界滑移均匀；Zn－10Al合金的α／β界面较Zn－5Al的少，超塑性也不如Zn－5Al的好；Zn-2.5Al合金的组织为（α＋β）＋β，（α＋β）共晶体主要包含α／β界面，超塑变形时易滑移，先共晶的β相包含β／β界面，超塑变形时不易发生滑移。随着拉伸速度的减小，合金的流变应力减小，延伸率增大。轧制变形量的合金，其超塑性也好。     

离心铸造Zn-Al-Mg-Si合金及其自生表面复合材料

采用热模金属型工艺，离心铸造Zn-27Al-9．8Mg-5．2Si和Zn-27Al-6．3Mg-3．7Si合金，获得了内层聚集大量块状初生Mg2Si、少量初生Si，中层不含初生Mg2Si、Si，外层含有初生Mg2Si、Si的自生表面复合材料．考察了成分、模具温度、转速、变质处理对离心铸造Zn-Al-Mg-Si合金组织和结构的影响．结果表明，Zn-27Al-9．8Mg-5．2Si合金自生复合材料内、外层的厚度比Zn-27Al-6．3Mg-3．7Si的厚度厚，初生Mg2Si的数量更多；随着转速增加，Zn-Al-6．3Mg-3．7Si合金自生复合材料的内层厚度增加，外层厚度减少；Na盐变质能够细化晶粒和初生Mg2Si，使初生Mg2Si分布更均匀，使初生Si团球化．最后分析了复合材料的成形过程．     

Zn-5%Al共晶合金超塑性变形特性的研究

研究了热轧态的Zn-5％Al共晶合金超塑性变形的力学行为及其显微组织的变化。结果表明:温度和应变速率对合金超塑性的力学性能影响很大。由于Zn-5％Al共晶合金具有优良的稳定组织,其最佳超塑性出现在较高的温度(300℃)和中等应变速率(1.67×10~(-4)s~(-1))条件下。随着温度提高到340℃,热长大已成为晶粒长大的主要因素。提高变形温度(300℃),可以使Zn-5％Al合金以较小的应力(25 MPa)和较高的应变速率(1.67×10~(-2)s~(-1))超塑性变形。     

Effects of Sn addition on microstructure and mechanical properties of Mg- Zn-Al alloys

The effects of Sn addition(0, 0.5, 1.0, 2.0 and 3 wt%) on microstructure of Mg-4Zn-1.5Al alloy in cast and extruded states were investigated, and the mechanical properties of as-extruded Mg-4Zn-1.5Al-xSn studied. The experimental results showed that the as-cast Mg-4Zn-1.5Al alloy was composed of two phases α-Mg and Mg_(32)(Al, Zn)_(49), while Sn-containing alloys consisted of α-Mg, Mg_(32)(Al, Zn)_(49) and Mg_2Sn phases, and Mg_(32)(Al, Zn)_(49) was not detected after extruding due to that the most of them dissolved into the matrix during the homogenized treatment. The addition of Sn refined the grains of as-cast and as-extruded Mg-Zn-Al alloys obviously. It was noted that the basal texture intensity reduced with increasing Sn content significantly in as-extruded Mg-Zn-Al alloys. The tensile tests results indicated that Sn addition improve the tensile strength of the extruded alloys,while it had a harmful effect on the ductility. When the addition of Sn was 2 wt%, the ultimate tensile strength(UTS), yield strength(YS) and elongation(ε_f) of the alloy were 280 MPa, 147 MPa and 17.4%, respectively.     

Sn对Mg-5Zn-2.5Al合金微观组织与性能的影响

利用光学显微镜、扫描电镜、万能试验机等分析测试设备研究了Sn对Mg-5Zn-2.5Al-xSn(x=0,1,2,3,4)(ZAT52x)合金组织结构及力学性能的影响.采用Thermo-Calc热力学软件计算了ZAT52x(x=0,2,4)3种合金在Scheil模型条件下液相质量分数与温度的关系以及凝固过程中的相变反应....     

Effects of Ce-rich RE on microstructure and mechanical properties of as-cast Mg-8Li-3Al-2Zn-0.5Nd alloy with duplex structure

The effects of Ce-rich RE on the microstructure and mechanical properties of as-cast Mg-8Li-3Al-2Zn-0.5Nd-x RE(x = 0, 1, 2, 3 wt%) alloys were investigated. The results indicated that the as-cast Mg-8Li-3Al-2Zn-0.5Nd alloy mainly consisted of α-Mg, β-Li, AlLi, MgLi2 Al and Al2 Nd phases. With the addition of Ce-rich RE in the alloy,Al3 RE and Al2 RE phases generated and gradually grew into net-like or block-like structure. With the addition of RE, Al-RE phases generated by consuming Al element and, thus, less Al element was dissolved in the matrix and less AlLi phase formed. Furthermore, less AlLi phase means that more Li element released to cause the increase ofβ-Li phase and refine the α-Mg phase. Under the influence of these factors, adding more RE led to higher elongation and lower tensile strength and hardness. With the addition of Ce-rich RE, the yield strength and ultimate tensile strength of the as-cast Mg-8Li-3Al-2Zn-0.5Nd alloy gradually decreased from 180 to 152 MPa and from 215 to 193 MPa, respectively, while the elongation was remarkably improved from 21.1% to 40.2%.     

Synergistic effect of Al and Gd on enhancement of mechanical properties of magnesium alloys

The effect of Gd/Al ratio on the properties of as-cast Mg-Gd-Al-Zn alloys was investigated by changing the chemical composition from that of AZ61 to GZ61. At the ratio of 1, the Al2Gd phase becomes predominant and Mg17Al12 is hardly seen in the microstructure. As a potent inoculant, the Al2Gd phase resulted in intense grain refinement and enhancement of strength, ductility and toughness. For instance, the tensile strength and elongation to failure of Mg-3Gd-3Al-1Zn alloy were enhanced by ~4% and 180% compared with those of AZ61 alloy, respectively. However, at high Gd/Al ratios, the Al2Gd phase was replaced by (Mg,Al)3Gd and Mg5Gd phases and very large grain sizes were achieved, which led to poor tensile properties and the appearance of cleavage facets on the fracture surfaces. Therefore, it can be deduced that the presence of Gd and Al, in appropriate amounts to reach Gd/Al ratio of ~ 1, is required for the achievement of grain refinement, good ductility, high strength, and the appearance of ductile fracture surfaces in the Mg-Gd-Al-Zn system. Conclusively, the Mg-Gd-Al-Zn alloys can be considered as a new class of structural magnesium alloy and it is superior to both AZ (Mg-Al-Zn) and GZ (Mg-Gd-Zn) series of alloys.     

Mg-5Zn-2Er-1.5Nd-xCa镁合金的显微组织和力学性能

利用光学显微镜、扫描电镜及其附带的能谱仪和电子万能试验机,研究了Mg-5Zn-2Er-1.5Nd-xCa(0.4相似文献   

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-5Zn-0.3Zr alloys behave as less noble cathodes in micro-galvanic corrosion and suppress the cathodic process. The additions of Nd and Y into Mg-5Zn-0.3Zr alloy also improve the compactness of the corrosion product film and are beneficial to the corrosion resistance.     

Al-6.6Zn-1.7Mg-0.26Cu合金挤压材焊接接头的组织与性能

采用光学显微镜、透射电子显微镜、维氏硬度计和拉伸试验机,研究了Al-6.6Zn-1.7Mg-0.26Cu合金挤压材熔化极惰性气体保护焊接接头的显微组织和力学性能。结果表明：焊缝中心区为枝晶,靠近母材侧的焊缝熔合区为柱状晶,母材为等轴晶,但靠近焊缝熔合区的母材晶粒发生了长大。焊接接头的硬度以焊缝为中心呈对称分布,从母材到焊缝中心,硬度先下降后上升再下降。焊缝中心区的硬度最低,为86～105（HV）。焊接接头的抗拉强度为309 MPa,屈服强度为237 MPa,伸长率为4.75%,挤压材的焊接强度系数为0.76。     

挤压变形对Mg-2.5Zn-0.5Ca合金组织与性能的影响

通过真空感应熔炼铸造法制备Mg-2.5Zn-0.5Ca合金,并对该合金铸态和挤压态试样分别进行显微组织、力学性能及断口形貌的对比分析.结果表明:经挤压变形后该合金发生动态再结晶,晶粒及Ca2Mg6Zn3沉淀相得到显著细化.挤压后屈服强度达222MPa,增大幅度高达204%,抗拉强度提高到291MPa.延伸率从铸态的11.5%上升至26%,经挤压变形后合金的断裂机制发生由脆性向韧性的转变,Ca2Mg6Zn3沉淀相为该合金的主要强化相.     

生物医用Zn-5Al合金的微观组织与性能

研究了生物医用Zn-5Al合金的微观组织结构演化,探讨了其组织对力学性能的影响.对铸态、均匀化处理和轧制态Zn-5Al合金的微观组织进行了表征,分析了合金的相组成,测试了轧制态Zn-5Al合金的力学性能.结果表明:铸态与均匀化处理后的Zn-5Al合金的相组成均主要为η-Zn相和α-Al相,铸态合金组织片层间距约为300nm.均匀化处理过程中发生了共析反应,合金中的α-Al相由铸态的长条形演变为球形共晶组织.经过总变形率85%的热轧变形后,Zn-5Al合金的屈服强度和抗拉强度分别为98MPa和130MPa,断裂延伸率达到74%.