Mg-11Y-5Gd-2Zn镁合金干滑动的摩擦磨损行为

采用往复式摩擦磨损试验机对铸态和T6态Mg-11Y-5Gd-2Zn合金进行干摩擦磨损试验,研究载荷（3~15N）、磨擦速度（0.03~0.24m/s）、摩擦温度（25~200 °C）对合金磨损率的影响,并通过扫描电镜观察合金磨损表面形貌和磨屑。结果表明：随着载荷的增加,合金的磨损率几乎呈线性增加;随着摩擦速率的增加,合金的磨损率降低;铸态合金的磨损率高于T6态合金的。Mg-11Y-5Gd-2Zn合金中的Mg12Y1Zn1相、表面氧化相和残留的磨屑影响合金的磨损率。在本试验条件下,磨损机制主要是粘着磨损和塑性变形。     

Effect of erbium on microstructure and thermal compressing flow behavior of Mg-6Zn-0.5Zr alloy

A series of thermal compressing tests of Mg-6Zn-0.5Zr and Mg-6Zn-0.5Zr-1Er alloys were performed on a Gleeble-1500D thermal simulator. The microstructures of thermal compressed Mg-6Zn-0.5Zr and Mg-6Zn-0.5Zr-1Er alloys were determined by optical microscopy, transmission electron microscopy and X-ray diffractometry. The results show that Mg-6Zn-0.5Zr alloy mainly consists of α-Mg and MgZn2 phase, while Mg-6Zn-0.5Zr-1Er alloy comprises α-Mg phase, coarse Mg3ZnnEr2 eutectic, rod-liked Mg3Zn4Er2 precipitated phase, fine I phase particle （Mg3Zn6Er, icosahedral quasicrystal structure）. The peak flow stress becomes larger with increasing strain rate and erbium addition at the same temperature, and gets smaller with increasing deformation temperature at the same strain rate. The deformation activation energy increases with increasing temperature, strain rate and erbium addition. In addition, it is observed that the growth of dynamic recrystallization （DRX） grains of Mg-6Zn-0.5Zr-lEr alloy was markedly suppressed due to the pinning effect of fine I phase and Mg3Zn4Er2 phase during thermal compression.     

Effects of microstructure on creep behavior of Mg-5%Zn-2%Al（-2%Y） alloy

Creep tests of Mg-5%Zn-2%Al（-2%Y） （mass fraction） alloy were carded out at 175 ℃ under the load of 50 MPa, on the cast and solution condition, respectively. Relationship between the creep behavior and microstructure was studied by the optical microscopy, SEM and TEM. The result shows that the primary creep strain is relative to the thermo-stability and the quantity of intermetallic compounds in grain boundary area. During the secondary creep period, the minimum creep rate of solution-treated specimens is substantially decreased as a result of dynamic MgZn2 precipitation.     

挤压态Mg-2Zn-0.5Gd-1Y-0.5Mn合金的组织特征、力学性能和体外腐蚀行为（英文）

为改善医用镁合金微观组织特征与降解行为,采用挤压形变工艺改变医用镁合金的晶粒尺寸特征及析出相/金属间化合物尺寸、分布规律,探究了挤压态医用Mg-2Zn-0.5Gd-1Y-0.5Mn镁合金微观结构特征及降解行为。结果表明：不同的热挤压变形并没有改变Mg-2Zn-0.5Gd-1Y-0.5Mn镁合金中第二相的类型,但改变了第二相的分布和形貌。Mg-2Zn-0.5Gd-1Y-0.5Mn镁合金的成分主为α-Mg和W-Mg₃Y₂Zn₃。电化学测试结果表明,铸态、挤压370℃和挤压390℃合金腐蚀电流密度分别为2.498、3.656、1.012μA·cm^-2。这是由于铸态组织中析出相/金属间化合物呈带状分布在基体中,可作为微阴极形成电偶腐蚀位点,加速合金腐蚀速率。合金在370℃挤压时,由于实际温度较低,部分粗化相未能充分溶解到α-Mg基体中,随着析出相数量增加及分布混乱无序,微阴极面积比例增大,进而导致腐蚀速率加剧。而390℃挤压态镁合金的挤压速度快、耗散行为慢,且铸锭与挤压机间摩擦强烈,已发生充分动态再结晶行为...     

Mg-7Gd-5Y-1Nd-2Zn-0.5Zr合金铸态及均匀化态微观组织

采用聚焦离子束定点切割技术(Focused ion beam,FIB),透射电镜(Transmission electron microscopy,TEM)、高角度环形暗场扫描透射电镜(High angle annular dark field scanning transmission electron micros...