不同尺寸Mg−Gd−Y−Zn−Ag镁合金零件冷却后的腐蚀行为

研究不同尺寸的Mg?6Gd?3Y?1Zn?0.3Ag(质量分数,％)镁合金零件冷却后的腐蚀行为.小型零件冷却较快,其显微组织由镁基体和粗大的长周期堆垛有序结构(LPSO)相组成.大型零件冷却较慢,其显微组织除镁基体和粗大的LPSO相外,晶粒内部有薄片状LPSO相析出.析氢测试结果表明,大型零件的腐蚀速度高于小型零件.交...     

固溶处理Mg-0.5Zr-1.8Zn-xGd生物可降解镁合金的微观组织、力学性能和腐蚀性能

研究了Mg-0.5Zr-1.8Zn-xGd (x=0,0.5,1.0,1.5,2.0,2.5,质量分数,%) 镁合金经过470 ℃和10 h固溶处理后的组织、力学性能和耐腐蚀性能。结果表明,Gd含量在0%~2.5%范围内,随着Gd含量增加,合金晶粒尺寸逐渐减小。当Gd含量低于1.5%时,合金元素几乎完全固溶于合金基体中,第二相主要由纳米尺度的(Mg,Zn)₃Gd析出颗粒组成。当Gd含量在1.5%~2.5%范围时,合金中出现未固溶的微米尺度的(Mg,Zn)₃Gd相,并且该相数量和尺寸随着Gd含量增加而增加。由于组织均匀分布和纳米尺寸的第二相颗粒存在,Mg-0.5Zr-1.8Zn-1.5Gd合金具有优异的力学性能和耐腐蚀性能。在120 h浸泡实验中,Mg-0.5Zr-1.8Zn-1.5Gd合金平均腐蚀速率首先降低,然后增加,接着缓慢降低,最后,随着浸泡时间延长,腐蚀速率最终变得稳定。     

Microstructures and Properties of As-Cast Mg92Zn4Y4 and Mg92Zn4Y3Gd1 Alloys with LPSO Phase

采用普通凝固技术制备了含有长周期堆垛有序 (long period stacking ordered, LPSO) 结构相的Mg92Zn4Y4和Mg92Zn4Y3Gd1合金。通过OM、SEM、EDS、XRD和TEM分析了合金中各相形貌、微区成分及结构。结果表明：Zn/RE原子比为1的2种铸态镁合金中均存在14H-LPSO结构相;在Mg-Zn-Y合金中添加稀土元素Gd增加了合金的形核质点并促进了长周期堆垛有序结构相的形成,14H-LPSO相体积分数由12.1%增至30.4%;LPSO结构相在高温形成时分割了a-Mg树枝晶,基体平均晶粒尺寸由50 μm降至10 μm以下;铸态Mg92Zn4Y4合金的凝固组织为a-Mg固溶体+Mg12ZnY+Mg3Zn3Y2+Mg-Y;铸态Mg92Zn4Y3Gd1合金的凝固组织主要为a-Mg固溶体+Mg12Zn(Y,Gd)+Mg3Zn3(Y,Gd)2;室温条件下,Mg92Zn4Y4和Mg92Zn4Y3Gd1合金的压缩率达到12.4%和15.5%,热导率分别为99.233和88.639 W·(m·K)-1。     

LPSO相增强铸态Mg_(92)Zn_4Y_4和Mg_(92)Zn_4Y_3Gd_1合金组织与性能分析（英文）

采用普通凝固技术制备了含有长周期堆垛有序(long period stacking ordered,LPSO)结构相的Mg92Zn4Y4和Mg92Zn4Y3Gd1合金。通过OM、SEM、EDS、XRD和TEM分析了合金中各相形貌、微区成分及结构。结果表明:Zn/RE原子比为1的2种铸态镁合金中均存在14H-LPSO结构相;在Mg-Zn-Y合金中添加稀土元素Gd增加了合金的形核质点并促进了长周期堆垛有序结构相的形成,14H-LPSO相体积分数由12.1%增至30.4%;LPSO结构相在高温形成时分割了αMg树枝晶,基体平均晶粒尺寸由50μm降至10μm以下;铸态Mg92Zn4Y4合金的凝固组织为α-Mg固溶体+Mg12Zn Y+Mg3Zn3Y2+Mg-Y;铸态Mg92Zn4Y3Gd1合金的凝固组织主要为α-Mg固溶体+Mg12Zn(Y,Gd)+Mg3Zn3(Y,Gd)2;室温条件下,Mg92Zn4Y4和Mg92Zn4Y3Gd1合金的压缩率达到12.4%和15.5%,热导率分别为99.233和88.639W·(m·K)-1。     

多孔Mg97Zn1Y2材料的力学性能与阻尼性能

多孔材料是一种新型轻质的结构-功能材料，具有较高的阻尼性能，同时兼具密度小、质量轻等特点，使其具有广阔的应用价值。基于此，选取含有长周期特殊结构相（LPSO相）的Mg97Zn1Y2为基体，以MgCO₃为发泡剂，SiC为增粘剂，通过熔体发泡法制备出镁基多孔材料，通过OM、SEM、TEM、XRD及DMA等技术手段，研究多孔Mg97Zn1Y2材料的力学性能、阻尼性能等。结果表明，多孔Mg97Zn1Y2材料主要由镁基体（α-Mg）、LPSO相和SiC相组成，当应变幅值较小时，多孔Mg97Zn1Y2复合材料的阻尼值明显优于Mg97Zn1Y2合金，随着孔隙率的增加，阻尼性能得到改善。孔隙率的增加降低了多孔Mg97Zn1Y2复合材料的抗压缩性能。此外，除了Mg97Zn1Y2合金本身的位错阻尼、界面阻尼和晶界阻尼之外，还有“气相”阻尼，共同影响着多孔Mg97Zn1Y2材料的阻尼性能。     

Zn含量对铸态Mg-Dy合金显微组织和力学性能的影响

研究添加不同含量Zn对铸态Mg-2Dy(摩尔分数,%)合金显微组织、时效行为和力学性能的影响。结果表明:Zn含量为0.5%和1%(摩尔分数)时,铸态合金中分别析出片层状具有18R类型长周期有序(LPSO)结构的Mg12Zn Dy相和粗大的Mg3Zn3Dy2相;同时,Zn的添加细化了合金的晶粒;固溶处理后,LPSO相由18R类型转变成沿晶内分布的细条状的14H类型,新的(Mg,Zn)x Dy相形成,且Mg3Zn3Dy2相的体积分数减小;添加0.5%Zn有效地增强了合金的时效硬化行为,提高了合金的室温和200℃的拉伸强度。     

Mg-Gd-Y-Zn-Zr稀土镁合金的组织性能

研究了Mg-Gd-Y-Zn-Zr合金中长周期堆垛有序结构(LPSO)对镁合金组织性能的影响。对铸态Mg-6Gd-2xYxZn-0.6Zr(质量分数,%)合金(x值取1、1.5、2、2.5,Y/Zn的质量比为2)进行X射线衍射分析、扫描电镜观察和能谱分析,拉伸试验和阻尼测试。结果表明,随着Y、Zn含量的增加,合金中镁基体减少、第二相增多,合金铸态相组成为Mg基体和Mg10(Gd,Y)Zn相。另外,组织得到细化,抗拉强度明显增加,塑性也有所提高,断裂机理由脆性解理断裂转变为准解理断裂。含有LPSO结构的镁合金的阻尼性能变化不能用单一的G-L理论解释。     

热处理对Mg-Gd-Cu合金组织和性能的影响

通过常规金属型铸造方法制备了Mg96Gd3Cu1(a%)合金。利用光学显微镜、X射线衍射仪、扫描电子显微镜和力学性能试验机等对合金的铸态和热处理态显微组织及力学性能进行了系统的分析。研究结果显示,铸态的合金中形成了14H类型的长周期堆垛有序结构相,固溶处理时,合金晶界处的Mg5Gd相溶解并析出层片状的14H长周期结构相。时效处理后合金性能得到较大的提高。     

Zn含量对Mg-Gd-Zn合金显微组织与力学性能的影响

研究了3种成分的Mg-11Gd-(1,1.5,2)Zn合金的显微组织和力学性能。结果表明,合金的铸态显微组织均由α-Mg基体、(Mg,Zn)3Gd共晶相和14H型LPSO相组成。铸态组织中(Mg,Zn)3Gd相的体积分数随Zn含量的增加而增大,且其热稳定性不断提高。同时,合金中LPSO相的体积分数也随Zn含量的增加而逐渐增大。合金在常温时的抗拉强度随着Zn含量的增加而降低,其中Zn含量较少的Mg-11Gd-1Zn合金在T6处理后呈现最高的强度和良好的塑性。当Zn含量较多时,合金T6处理的效果却远低于T5处理。随Zn含量的增加,合金在200℃高温下的抗蠕变性能也略有下降,但3种合金的抗蠕变性能都优于WE54合金。     

固溶处理对压铸GZ142合金显微组织的影响

借助XRD、SEM、EDX和TEM检测手段,对比了固溶处理前后压铸GZ142合金的显微组织。结果表明,固溶处理前压铸GZ142合金由α-Mg基体和(Mg, Zn)₃Gd共晶次生相组成,在400 ℃下固溶处理1 h后,晶内生成了大量层状14H型的长周期堆垛有序结构（LPSO）,同时,部分(Mg, Zn)₃Gd共晶次生相转变成同样具有长周期堆垛有序结构的X相。     

Effect of Al addition on microstructure and mechanical properties of Mg−Gd−Zn alloys

The microstructure evolution and mechanical properties of Mg?15.3Gd?1Zn alloys with different Al contents (0, 0.4, 0.7 and 1.0 wt.%) were investigated. Microstructural analysis indicates that the addition of 0.4 wt.% Al facilitates the formation of 18R-LPSO phase (Mg₁₂Gd(Al, Zn)) in the Mg?Gd?Zn alloy. The contents of Al₁₁Gd₃ and Al₂Gd increase with the increase of Al content, while the content of (Mg, Zn)₃Gd decreases. After homogenization treatment, (Mg, Zn)₃Gd, 18R-LPSO and some Al₁₁Gd₃ phases are transformed into the high-temperature stable 14H-LPSO phases. The particulate Al?Gd phases can stimulate the nucleation of dynamic recrystallization by the particle simulated nucleation (PSN) mechanism. The tensile strength of the as-rolled alloys is improved remarkably due to the grain refinement and the fiber-like reinforcement of LPSO phase. The precipitation of the β′ phase in the peak-aged alloys can significantly improve the strength. The peak-aged alloy containing 0.4 wt.% Al achieves excellent mechanical properties and the UTS, YS and elongation are 458 MPa, 375 MPa and 6.2%, respectively.     

微量Ca添加对铸造Mg-Sm-Gd基合金显微组织与力学性能的影响（英文）

主要通过透射电子显微镜、高角度环形暗场扫描透射电子显微镜和拉伸测试研究微量Ca元素对Mg-Sm-Gd-Zn-Zr合金显微组织和力学性能的影响。结果表明,Mg-Sm-Gd-Zn-Zr合金中主要第二相为Zn元素富集的Mg₃RE相,Ca元素添加不仅可以细化晶粒,还可以促进Mg₅RE相和溶质原子富集的层错形成。此外,共格界面表明Mg₃RE相可以作为Mg₅RE相的形核位点,这些均有利于合金力学性能的提高。     

Effect of Y addition on microstructure and mechanical properties of Mg–Zn–Mn alloy

The effects of Y on the microstructure and mechanical properties of Mg–6Zn–1Mn alloy were investigated. The results show that the addition of Y has significant effect on the phase composition, microstructure and mechanical properties of Mg–6Zn–1Mn alloy. Varied phases compositions, including Mg₇Zn₃, I-phase (Mg₃YZn₆), W-phase (Mg₃Y₂Zn₃) and X-phase (Mg₁₂YZn), are obtained by adjusting the Zn to Y mass ratio. Mn element exists as the fine Mn particles, which are well distributed in the alloy. Thermal analysis and microstructure observation reveal that the phase stability follows the trend of X>W>I>Mg₇Zn₃. In addition, Y can improve the mechanical properties of Mg–Zn–Mn alloy significantly, and the alloy with Y content of 6.09% has the best mechanical properties. The high strength is mainly due to the strengthening by the grain size refinement, dispersion strengthening by fine Mn particles, and introduction of the Mg–Zn–Y ternary phases.     

Effect of Gd on microstructure,mechanical properties,and corrosion behavior of as-homogenized Mg−8Li−3Al−2Zn−0.2Zr alloy

The microstructure observation, tensile test, electrochemical measurement, and corrosion morphology characterization were conducted to study the effect of Gd on the microstructure, mechanical properties, and corrosion behavior of as-homogenized Mg?8Li?3Al?2Zn?0.2Zr (LAZ832?0.2Zr) alloy. The addition of trace Gd can improve the mechanical properties of as-homogenized LAZ832?0.2Zr alloy by refining the microstructure, reducing the content of AlLi softening phase, and forming Al₂Gd strengthening phase. Meanwhile, the addition of trace Gd can weaken the microgalvanic corrosion between matrix phase and AlLi phase, inhibit the galvanic corrosion between α-Mg phase and β-Li phase, and result in the formation of dense oxide film containing Gd₂O₃, thereby improving the corrosion resistance of the alloy. When the Gd content is 1.0 wt.%, the alloy shows the best comprehensive properties with the ultimate tensile strength of 189.8 MPa, elongation of 42.3%, and corrosion rate (determined by hydrogen evolution) of 0.86 mm·a^?1.     

Effect of Gd content on microstructure and dynamic mechanical properties of solution-treated Mg−xGd−3Y−0.5Zr alloy

The effect of Gd content ranging from 6.5 wt.% to 8.5 wt.% on microstructure evolution and dynamic mechanical behavior of Mg?xGd?3Y?0.5Zr alloys was investigated by optical microscopy, X-ray diffraction, scanning electron microscopy and split Hopkinson pressure bar. The microstructure of as-cast Mg?xGd?3Y?0.5Zr alloys indicates that the addition of Gd can promote grain refinement in the casting. Due to the rapid cooling rate during solidification, a large amount of non-equilibrium eutectic phase Mg₂₄(Gd,Y)₅ appears at the grain boundary of as-cast Mg?xGd?3Y?0.5Zr alloys. After solution treatment at 520 °C for 6 h, the Mg₂₄(Gd,Y)₅ phase dissolves into the matrix, and the rare earth hydrides (REH) phase appears. The stress?strain curves validate that the solution-treated Mg?xGd?3Y?0.5Zr alloys with optimal Gd contents maintain excellent dynamic properties at different strain rates. It was concluded that the variation of Gd content and the agglomeration of residual REH particles and dynamically precipitated fine particles are key factors affecting dynamic mechanical properties of Mg?xGd?3Y?0.5Zr alloys.     

Zn元素对Mg-25Sn合金组织和力学性能的影响

以Mg 粉、Sn 粉和Zn 粉为初始原料,采用机械合金化和热压烧结的方法制备Mg-25Sn-xZn 合金.研究了Zn 添加量对Mg-25Sn 合金显微组织和性能的影响.结果表明:Mg-25Sn-xZn 体系的机械合金化过程中,Zn 元素不参与合金化反应,但Zn 的引入降低了Mg+Mg2Sn 混合物的尺寸.除固溶外,烧结...     

氯化物熔盐体系共电沉积法制备Mg-Li-Gd合金的研究

在LiCl-KCl-MgCl2-Gd2O3熔盐体系中采用电化学共沉积法制备Mg-Li-Gd合金,借助循环伏安和计时电位技术对熔盐电化学行为进行探讨,并运用XRD,SEM,EDS和OM对所得合金进行测试.研究结果表明,Gd2O3在LiCl-KCl熔盐体系中几乎不溶,而在LiCl-KCl-MgCl2熔盐中有一定的溶解度,而...     

Refinement and strengthening mechanism of Mg−Zn−Cu−Zr−Ca alloy solidified under extremely high pressure

Mg?Zn?Cu?Zr?Ca samples were solidified under high pressures of 2–6 GPa. Scanning electron microscopy and electron backscatter diffraction were used to study the distribution of Ca in the microstructure and its effect on the solidification structure. The mechanical properties of the samples were investigated through compression tests. The results show that Ca is mostly dissolved in the matrix and the Mg₂Ca phase is formed under high pressure, but it is mainly segregated among dendrites under atmospheric pressure. The Mg₂Ca particles are effective heterogeneous nuclei of α-Mg crystals, which significantly increases the number of crystal nuclei and refines the solidification structure of the alloy, with the grain size reduced to 22 μm at 6 GPa. As no Ca segregating among the dendrites exists, more Zn is dissolved in the matrix. Consequently, the intergranular second phase changes from MgZn with a higher Zn/Mg ratio to Mg₇Zn₃ with a lower Zn/Mg ratio. The volume fraction of the intergranular second phase also increases to 22%. Owing to the combined strengthening of grain refinement, solid solution, and dispersion, the compression strength of the Mg–Zn–Cu–Zr–Ca alloy solidified under 6 GPa is up to 520 MPa.     

Ce、Y和Gd对Mg-3Sn-2Sr镁合金铸态组织和力学性能的影响(英文)

通过扫描电镜、X射线衍射、差热分析以及抗拉和蠕变性能测试等手段,调查和比较了Ce、Y和Gd对Mg-3Sn-2Sr镁合金铸态组织和力学性能的影响。结果表明:Mg-3Sn-2Sr三元合金主要由?-Mg、初生和共晶SrMgSn以及Mg2Sn相组成。当添加1.0%Ce、1.0%Y和1.0%Gd到Mg-3Sn-2Sr合金后,合金中分别形成了Mg12Ce、YMgSn、GdMgSn和/或Mg17Sr2相。同时,合金中初生SrMgSn相的形成被抑制,且呈针状的粗大初生SrMgSn相也被变质和细化。此外,添加1.0%Ce、1.0%Y和1.0%Gd均能同时改善Mg-3Sn-2Sr合金的抗拉性能和蠕变性能。在含Ce、Y和Gd合金中,含Ce合金的抗拉性能相对较含Y和含Gd合金的高。     

Gd添加量对Zn-1.2Cu-1.2Mg锌合金组织和性能的影响

研究了Zn-1.2Cu-1.2Mg-xGd（x=0,0.1,0.25,0.5,质量分数,%）锌合金微观组织、在模拟体液中的腐蚀行为和力学性能。结果表明,锌合金组织主要由Zn固溶体和Mg₂Zn₁₁金属间化合物组成。当Gd添加量为0.5%时,形成了GdZn₁₂化合物。锌合金的硬度随Gd添加量的增加而增加,在0.5% Gd添加量时,硬度达到最大值为1530 MPa。在0.25% Gd添加量时锌合金具有高的抗拉伸强度,而在0.1% Gd添加量时锌合金具有最低的腐蚀速率。