Al-Mg-Si合金和Al-Mg-Si-0.6%Cu合金的内耗研究

采用低频力学谱仪对Al-Mg-Si合金和Al-Mg-Si-0.6%Cu合金的内耗进行了研究。结果表明:两种合金的内耗在加热过程先升高后降低。利用TEM对Al-Mg-Si合金和Al-Mg-Si-0.6%Cu合金的微观结构进行观察,显示合金内耗的变化是合金中的析出相和位错相互作用的结果。

Cu质量分数对Al-1.0Mg-1.0Si-0.6Mn合金显微组织和性能的影响

利用硬度测试、室温拉伸实验、晶间腐蚀实验、电化学腐蚀实验、SEM和TEM等方法,研究Cu质量分数对Al-1.0Mg-1.0Si-0.6Mn合金显微组织与性能的影响。研究结果表明:随着Al-1.0Mg-1.0Si-0.6Mn合金中Cu质量分数由0.01%逐渐增加至1.12%,其达到峰值时效所需时间逐渐减少,且峰值时效(T6态)硬度明显增加;随着Cu质量分数的增加,峰时效状态合金的抗拉强度由357.7 MPa逐渐增加至452.2 MPa,抗拉强度提升94.5 MPa,这是因为随着Cu质量分数增加,晶内析出相数量逐渐增多且尺寸逐渐减小,使得沉淀强化效果逐渐增强;Cu质量分数增加使粗大相AlFeMnSi的数量逐渐增加,腐蚀电流密度显著增大,合金的断后伸长率和抗晶间腐蚀性能呈下降趋势。

Residual stress and precipitation of Mg-5Zn-3.5Sn-1Mn-0.5Ca-0.5Cu alloy with different quenching rates

The effect of the quenching rate after solution treatment on the residual stress and precipitation behavior of a high strength Mg-5 Zn-3.5 Sn-1 Mn-0.5 Ca-0.5 Cu plate is studied.The simulation results show decreasing temperature gradient in the plate with decreasing quenching rate,which leads to weakened inhomogeneous plastic deformation and decreased residual stress.No dynamic precipitation on the grain boundary happens after either cold water cooling or air cooling,however,air cooling leads to dynamic precipitation of Mg-Zn phase on Mn particles around which a low-density precipitate zone develops after aging treatment.Moreover,the fine and densely distributed Mg-Zn precipitates observed after aging treatment of the cold water cooled alloy are replaced by coarse precipitates with low density for the air cooled alloy.Both the low-density precipitate zone near Mn particles and the coarsening of precipitates are the source of the decrease in hardness and tensile properties of the air cooled alloy.The residual stress drops faster than the hardness with decreasing quenching rate,which makes it possible to lower the residual stress without sacrificing too much age-hardening ability of the alloy.

Microstructure of Rapidly Solidified Al-3.8Li-0.8Mg-0.4Cu-0.13Zr Alloy by Spray Deposition Processing

谷物是在尺寸的 5-20 亩 m，并且微观结构展出快速的团结优点。收缩孔被避免了，并且优先的粒子边界的形成被阻止了到大程度。但是仍然在那里存在有各种各样的形状的一些微毛孔。相对密度同样 -- 扔的材料平均是 94% 。主要在测试合金猛抛是三角洲(AlLi ) ， S (Al//2CuMg ) 和三角洲素数(Al//3Li ) 分阶段执行。(编辑作者摘要) 10 个裁判员。

Microstructure and yield phenomenon of an extruded Mg-Y-Cu alloy with LPSO phase

A yield phenomenon was firstly reported in an extruded Mg-6.8Y-2.5Cu alloy and the corresponding microstructure was also investigated in this work,The cast alloy is mainly composed ofα-Mg,18R long period stacking order(LPSO)phase,eutectic phase(Mg_(20)Cu_(4)Y_(1)),and Mg_(2)Cu phase.The 18R LPSO phase at the dendritic grain boundary transforms into the 14H LPSO phase in the grain interior during homogenization.After extrusion,the grain size of the homogenized alloy is remarkably refined to-3.69μm and the second phase is significantly broken and distributed in the extrusion direction.Tensile testing curves of the extrude alloy at room temperature indicate that the yield strength and ultimate tensile strength increase while the elongation of the alloy decreases with increasing strain rate.Interestingly,a yield plateau fo rms and gradually decreases with increasing strain rate.The yield phenomenon is related to the dislocation multiplication and the interaction between the movable dislocations and solute atoms.

新型Al-6Zn-2.5Mg-0.6Cu合金的均匀化工艺

采用差热分析仪(DSC)、光学显微镜(OM)、扫描电镜(SEM)、透射电镜观察(TEM)、布氏硬度测试等方法研究了一种新型Al-6Zn-2.5Mg-0.6Cu(mass%)合金在单、双级均匀化过程的组织性能演变。结果表明:Al-6Zn-2.5Mg-0.6Cu(mass%)合金铸锭组织中存在着严重的枝晶偏析,由ɑ(Al)和T(Al-Mg-Zn-Cu)四元相组成的非平衡共晶相沿晶界呈连续链状分布;合金经470℃×24 h均匀化处理过后,铸锭晶界得到了明显的净化,晶界上原本大量存在的非平衡共晶相回溶入基体中;铸锭先在250℃×4C h下进行均匀化预处理有利于获得尺寸细小、均匀分布的含Mn、Cr析出相,提高合金的布氏硬度值,确定该新型合金铸锭的最优均匀化工艺为250℃×4 h+470℃×24 h。

脉冲磁场对镁铜合金组织、力学性能及生物腐蚀行为的影响

在生物医用Mg-0.6Cu合金的凝固过程中施加脉冲磁场处理,研究脉冲电压对合金凝固组织、力学性能及生物腐蚀行为的影响。结果表明:随着放电电压的增加,在合金凝固组织逐渐细化的同时,第二相的数量也逐渐降低;当脉冲电压为300 V时,合金的屈服强度、抗拉强度和伸长率均逐渐提高,其较未处理合金分别提高了49.4%、45.7%和114.3%;试样在37℃的SBF溶液中的析氢速率、腐蚀速率和自腐蚀电流密度均逐渐降低,同时,其自腐蚀电位也逐渐向正向移动,这表明合金的耐腐蚀性能逐渐提高。

Microstructure and mechanical properties of Mg-Gd-Y-Sm-Al alloy and analysis of grain refinement and strengthening mechanism

The effects of Sm on the microstructure and mechanical properties of Mg-11 Gd-2 Y-0.6 Al alloy were investigated by X-ray diffraction,optical microscopy,scanning electron microscopy,energy dispersive spectrometry and high resolution transmission electron microscopy.Based on the theory of edge—edge matching and electronegativity theory,the mechanism of grain refinement is discussed.The strengthening mechanism is expounded conveniently from fine grain strengthening,coherent strengthening,precipitation strengthening and grain boundary strengthening.The results show that the micro structure of Mg-11 Gd-2 Y-0.6 Al alloy is mainly composed of a-Mg matrix,Mg5 Gd and Mg24Y5 phases.The addition of Sm forms Mg41Sm5 phase in the alloy and refines the alloy.The addition of Sm significantly improves the mechanical properties of the alloy at room and high temperatures.When the addition of Sm is 3 wt%,the tensile strengths of the alloy at room temperature and high temperature(200℃)reach the maximum value 292 and 321 MPa,respectively.The fracture mode of the alloy at different temperatures is mainly brittle fracture and intercrystalline fracture.

绿色建筑铝合金型材的热处理与力学性能

采用金相显微镜、扫描电镜、透射电镜和拉伸试验机等手段,研究了固溶时间、时效温度和时效时间对Al-1.0Mg-0.6Si-0.25Cu合金显微组织、硬度和拉伸性能的影响。研究结果表明,固溶温度540℃、固溶保温时间60 min时,合金中黑色块状Mg2Si初生相基本回溶至基体,而继续延长保温时间,白色条状或块状AlFeSi相不会发生明显变化,而晶粒发生粗化;随着固溶保温时间的延长,合金的抗拉强度、屈服强度和硬度都呈现先增加而后减小的特征,断后伸长率先减小而后增大;随着时效温度升高,时效时间延长,合金中细小第二相数量不断增多,晶粒有所粗化,合金的抗拉强度、屈服强度和硬度都呈现先增加而后减小的特征,断后伸长率先减小而后增大。Al-1.0Mg-0.6Si-0.25Cu合金适宜的固溶保温时间为60 min、时效温度为180℃、时效时间为7 h。