Ca对Mg-8Al镁合金显微组织和力学性能的影响

对Mg-8Al合金加不同含量Ca后的镁合金显微组织进行观察,结合XRD、EDS能谱分析,研究了Ca合金化对Mg-8Al合金组织和性能的影响。结果表明:Mg-8Al合金通过Ca合金化后,铸态显微组织得以细化,共晶β-Mg17Al12相变得断续、细小;合金组织中有新相Mg2Ca形成,由于Ca原子与Mg原子的置换作用,使β-Mg17Al12相中也存在Ca元素;合金化后的组织综合力学性能有所提升,尤以Mg-8Al-0.5Ca合金性能最优,这较合金化前有大幅提高。     

铸态Mg-4Al-2Si合金的显微组织与高温力学性能

采用光学显微镜、扫描电子显微镜、XRD衍射和拉伸试验等方法,研究了Mg-4Al-2Si(s42)镁合金的铸态组织和高温力学性能.结果表明,铸态合金主要由a-Mg基体、β-Mg17Al12相和Mg2Si相组成.其中,离异共晶β-Mg17Al12相呈网状分布于晶界上,初生Mg2Si相呈多边形块状随机分布于基体组织中,共晶Mg2Si相呈粗大的汉字状沿晶界或穿晶分布;150℃高温短时拉伸,合金的抗拉强度为97MPa,屈服强度为58MPa,伸长率为18%,拉伸断裂形式为准解理脆性断裂.     

固溶处理对铸态Mg-4Al-2Si合金组织和性能的影响

研究了固溶处理对铸态Mg-4Al-2Si(AS42)合金组织和性能的影响.结果表明,铸态与热处理态合金均由α-Mg基体、β-Mg17Al12相和Mg2Si相3部分组成.固溶处理使合金中的β-Mg17Al12相发生部分溶解,汉字状Mg2Si相颗粒出现球状化,合金的力学性能有较大幅度的提高.铸态与热处理态合金的断裂形式均为准解理脆性断裂.     

Mg-5Al-0．8Ca-0．2La-xSr合金的显微组织及高温力学性能

采用真空熔化、精炼和无氧化重力铸造工艺,制备了不同Sr含量的Mg-5Al-0.8Ca-0.2La镁合金试样.研究了Sr对该镁合金的显微组织、室温与150～200 ℃温度区间内力学性能的影响.结果表明:基体合金组织除含α-Mg相外,主要由骨骼状和条状的Al2Ca相、点状的Al11La3颗粒相以及少量的β-Mg17Al12相组成;Sr的加入显著细化了基体合金的显微组织,抑制β-Mg17Al12相的析出,并在晶界上析出Mg-Al-Sr三元耐热相,提高了合金的高温力学性能;随着Sr含量的增加,虽然合金的室温抗拉强度和伸长率呈下降趋势,但合金的高温抗拉强度(σb)和屈服强度(σ0.2)得到明显提高;当Sr含量在0.5%时,合金的综合力学性能最佳.     

Mg-Al-Sm系耐热镁合金的显微组织和力学性能(英文)

分析铸态和压铸态Mg-6.02Al-1.03Sm、Mg-6.05Al-0.98Sm-0.56Bi和Mg-5.95Al-1.01Sm-0.57Zn合金的显微组织和相组成,测试其拉伸力学性能与流动性能。结果表明,Mg-6.02Al-1.03Sm合金铸态组织由δ-Mg基体、半连续的δ-Mg17Al12相和高热稳定性的小块状Al2Sm相组成。添加Bi后生成杆状Mg3Bi2相,而添加的Zn固溶于δ-Mg基体和δ-Mg17Al12相中。铸态合金呈现优异的拉伸力学性能,室温时其抗拉强度(δb)和伸长率(δ)分别达到205~235 MPa和8.5%~16.0%,而423 K时分别超过160 MPa和14.0%。压铸态组织明显细化,第二相发生破碎,且弥散分布。压铸态合金呈现更高的拉伸力学性能和优异的流动性能,室温δb和δ分别达到240~285 MPa和8.5%~16.5%,流动长度可达1870~2420 mm。压铸态室温拉伸断口呈现明显的断裂特征。     

Ca含量对Mg-Al-Sr-Mn合金组织和性能的影响

采用OM、XRD、SEM等方法研究了不同Ca含量对Mg-3.5Al-0.4Sr-0.5Mn合金显微组织和力学性能的影响。结果表明,铸态合金的显微组织主要包括α-Mg相和β-Mg17Al12相。加入适量碱土金属Ca后,部分Ca溶到β相中,并有新相Al2Ca生成。随着Ca含量的增加,合金的强度和断后伸长率均呈先增大后减小的趋势,且都在1.0%Ca时达到最高。     

Zn及固溶时效对Mg-4Al-2Ca合金组织和性能的影响

通过Mg-4Al-2Ca-xZn系镁合金的设计,研究添加不同含量的Zn对合金微观组织及力学性能的影响。分析得出,铸态Mg-4Al-2Ca合金组织主要由α-Mg、β-Mg17Al12相和少量Al2Ca相组成;当合金中添加2%、4%和6%的Zn后,随着Zn含量的增加合,金的初生相α-Mg变化明显,合金组织中Al2Ca相增加,形成了Mg32(Al,Zn)49相、MgZn相和少量Mg5Zn2Al2化合物;在Zn含量为6%时,合金的初生相α-Mg细化明显,且具有等轴状形态。在时效时间相同的情况下,Zn元素的增加使α-Mg相细化,在相界处析出相减少。经过340℃保温20 h固溶后,在180℃进行一系列的时效处理结果的分析表明,时效72 h时,Mg-4Al-2Ca-xZn(x=0,2,4,6)合金的硬度都达到最大值,分别为72.9、75.1、80.7和83.9 HB,硬度值随Zn含量的增加而增大。     

Mg-8Al-Sr-xCa (x=0.5, 1.0, 1.5) 合金的显微组织和力学性能

研究了Mg-8Al-Sr-xCa合金的显微组织和力学性能。铸态合金组织主要由α-Mg相和β-Mg17Al12相组成。在Ca添加至1.5%(质量分数,下同)后,形成少量Al2Ca颗粒。挤压过程中合金发生了动态再结晶,晶粒明显细化,同时第二相碎化,时效后组织中的β相趋于球形。拉伸结果显示,在Ca含量由0.5%增至1.5%时,铸态和挤压时效态合金的拉伸性能逐渐提高。挤压时效态AJ80+1.5%Ca的屈服强度和抗拉强度分别为274 MPa和327 MPa,该合金优异的拉伸强度主要是细晶强化和Al2Ca颗粒与含Ca的β-Mg17Al12相析出强化的结果。     

Mg-6Al-1Zn-xSi合金的显微组织与高温力学性能

采用重力铸造法制备了不同Si含量的Mg-6Al-1Zn-x Si合金,分析了合金的显微组织,测试了合金在150℃下的拉伸力学性能。结果表明,合金均由α-Mg基体、β-Mg17Al12和Mg2Si相组成。随着Si含量的增加,α-Mg基体晶粒的平均尺寸逐渐减小,Mg2Si颗粒的平均尺寸逐渐增大;β-Mg17Al12由分布于晶界及晶内的点状转变为网状分布于晶界上;合金的高温抗拉强度、屈服强度和伸长率逐渐提高。此外,高温拉伸断裂形式为准解理脆性断裂。     

Mg-9AI-6Si镁合金组织及性能研究

利用普通重力铸造方法,制备了Mg-9Al-6Si镁合金.用光镜(OM),扫描电镜和能谱仪(SEM/EDS)研究了铸态Mg-9Al-6Si镁合金的显微组织,用XRD分析了合金的相组成,测试了合金室温拉伸力学性能和硬度,用SEM观察了合金拉伸断口形貌.结果表明:Mg-9Al-6Si镁合金铸态组织主要由α-Mg基体和分布在其上的粗大棱状枝晶或多边形块状初晶Mg2Si相及连成网状的β-Mg17Al12相组成,无汉字状Mg2Si相.该合金室温拉伸断口是以准解理断裂为主的脆性断裂,断裂沿α-Mg基体和Mg2Si相的界面处产生并扩展,抗拉强度为137.45 MPa,硬度为123 Hv1.     

稀土钇对铸态Mg-8Li-3Al-3Zn合金显微组织和力学性能的影响

镁锂(Mg-Li)合金是现今最轻的金属结构材料,在航空航天及交通运输等领域具有重大的应用价值。但铸造镁锂合金绝对强度低限制了其发展和应用。在Mg-Li二元合金中添加铝(Al)、锌(Zn)和稀土元素钇(Y)三种强化元素制备Mg-Li-Al-Zn-Y五元铸态镁锂合金来提高镁锂合金的力学性能。利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)和力学性能测试对比研究添加稀土Y前后铸态Mg-8Li-3Al-3Zn合金中相组成、微观组织和力学性能,揭示稀土元素Y对铸态Mg-8Li-3Al-3Zn合金的增强机制和断裂机理。结果表明:铸态Mg-8Li-3Al-3Zn合金主要包含3种相:基体α-Mg、第二相AlLi和MgLi2Zn。添加1.0%(质量分数)Y后,铸态镁锂合金中AlLi相消失,并析出了大量富集在α-Mg晶界处的硬质Al2Y相,合金的晶粒发生细化。与Mg-8Li-3Al-3Zn(抗拉强度134.40 MPa、屈服强度96.46 MPa和伸长率7.5%)相比,Mg-8Li-3Al-3Zn-1Y抗拉强度、屈服强度和伸长率依次为189.99 MPa、128.2 MPa和7.8%,分别提高了41.4%、32.9%和4%。合金的断裂方式由解理断裂转变为准解理断裂。铸态镁锂合金力学性能的提高主要归因于Al2Y的形成及其对α-Mg相的细化作用。     

Ce 含量对 Mg2.2Sn1Al0.5Zn合金显微组织和力学性能的影响

利用 OM、XRD、SEM、EDS 等方法,研究了不同Ce 含量对 Mg-2.2Sn-1Al-0.5Zn 合金显微组织和力学性能的影响。结果表明：添加适量的稀土 Ce 能细化晶粒,Ce 与 Al 结合形成高熔点的稀土相 Al4Ce,使β-Mg17Al12相数量减少;针状或杆状 Al4Ce 相分布在晶界周围,阻止了位错运动;合金的抗拉强度、塑性和硬度均随 Ce 含量的增加呈现先增加后降低的趋势,当 Ce 含量为0.6%时合金的力学性能最佳。对断口进行扫描分析证明拉伸断裂为穿晶断裂和韧性断裂的混合断裂。     

Microstructure and creep properties of Mg-4Al-2Sn-1 （Ca,Sr） alloys

The effects of Ca and Sr addition on the microstructure and creep properties of Mg-4Al-2Sn alloys were examined.Tensile tests at 25℃ and 200℃ and creep tests at 150℃ and 200℃ were carried out to estimate the room temperature and high temperature mechanical properties of these alloys.The microstructure of the Mg-4Al-2Sn alloy showed dendriticα-Mg,Mg17Al12 and Mg2Sn phases.The latter two phases precipitated along the grain boundaries.The addition of Ca and Sr resulted in the formation of ternary CaMgSn and SrMgSn phases within the grain.The grain size was reduced slightly with the addition of Sr and Ca.The tensile strength was decreased by the addition of Ca and Sr at room temperature.However,the high temperature tensile strength was increased.The creep strength was improved by the addition of Ca and Sr.     

冷却速度对Mg-5Al-0.5Y合金组织和性能的影响

利用光学显微镜、扫描电镜、X射线衍射仪和硬度测试仪等试验手段,研究了金属型、石墨型及砂型铸造Mg-5Al-0.5Y合金分别在冷却速度为200、150和60℃/min时的微观组织和硬度的变化,并对其机理进行分析。结果表明,随着冷却速度的降低,α-Mg晶粒粗化,晶粒平均尺寸从52.83μm增大到68.96μm,增幅30.53%,而离异共晶β-Mg17Al12相从连续网状分布变为粗大的断续分布,相对含量也由10.35%减少至8.67%,降幅为16.23%;冷却速度的降低及晶粒的粗大化,还致使合金硬度也随之下降,由56.4(HV)降至51.3(HV)。     

铸态Mg-4Al-4Si合金的显微组织与力学性能

摘 要:采用重力铸造法制备Mg-4A1-4Si(AS44)镁合金,研究铸态合金的显微组织和室温力学性能.结果表明,铸态AS44合金主要由α-Mg基体、β-Mg17Al12相及Mg2Si相组成;Mg2Si粗大的呈树枝状、块状和汉字状3种形态;铸态合金的硬度为66.5 HV3,室温抗拉强度为108.8 MPa,屈服强度为72.3 MPa,伸长率为2.6％;拉伸断裂形式为准解理脆性断裂.     

Effects of yttrium on microstructure and mechanical properties of Mg-6Al magnesium alloy

Since Y has a great solid solubility in magnesium alloys, it helps enhancing the heat-resistant property of magnesium alloys. The effects of Y on microstructures and mechanical properties of Mg-6Al alloy have been studied in this work. The results show that Y addition refines grains of Mg-6Al alloy, and reduces the amount of the Mg 17 Al 12 phase. At the same time, the high melting-point Al 2 Y phase particles are formed. According to the mathematical model of the two-dimensional lattice misfit proposed by Braffit, it is believed that the Al 2 Y particles can serve as the nucleation sites for α-Mg. After T6 treatment, both elongation and ultimate tensile strength of Mg-6Al alloy at the room temperature and high-temperature increased firstly and then decreased, with increasing Y addition. The peak mechanical properties were achieved in the Mg-6Al-1.2Y alloy system. Y addition appears to change the fracture characteristic of Mg-6Al alloy. With 1.2wt%Y, the fracture surface of the alloy showed a lot of dimples and tearing ridges which connected the microscopic dimples and the fracture is mixed fracture of quasi-cleavage and ductile fracture.     

Influence of aging modes on microstructure and mechanical properties of AZ80 magnesium alloy

The microstructure and mechanical properties of AZ80 magnesium alloy after solid solution and aging treatments were studied by using optical microscope (OM), X-ray diffraction (XRD), scanning electron microscopy(SEM) as well as tensile testing. The results indicated that β-Mg17Al12 phase was getting to distribute discontinuously along the grain boundary after treated at 395℃ ageing for 12 h followed by water-cooling, but it did not dissolve into α-Mg completely. The residual β-Mg17Al12 phase distributed along the grain boundary and had block-like or island shapes. The size of α-Mg was getting to be coarsening but not significantly. The β-Mg17Al12 precipitates appeared in discontinuous and continuous patterns from supersaturated α-Mg solid solution after aged at 200℃. The precipitation patterns were associated with the aging time essentially. The tensile strength and elongation of the alloy increased significantly but the hardness and yield strength decreased after solid solution treatment. However, with the prolonging of aging time, the hardness and strength of alloy increased while the ductility decreased.     

Microstructures and Mechanical Properties of Mg–xAl–1Sn–0.3Mn( x = 1, 3, 5) Alloy Sheets

The influence of Al alloying on the microstructures and the mechanical properties of Mg–x Al–1 Sn–0.3 Mn alloy sheets was investigated. The microstructure of Mg– x Al–1 Sn–0.3 Mn consisted of α-Mg and Mg 17 Al 12 precipitates. Alloying with Al increased the amount of Mg_(17)Al_(12) and the average grain size. Uniaxial tensile tests were carried out along the extrusion direction(ED), the transverse direction(TD) and 45° toward the ED. Mg–5 Al–1 Sn–0.3 Mn alloy sheet exhibited the best combination of mechanical properties along the ED: a yield strength of 142 MPa, an ultimate tensile strength of 282 MPa and an elongation of 23%. The good performance of Mg–5 Al–1 Sn–0.3 Mn sheet was mainly attributed to the large quantity of Mg_(17)Al_(12) precipitates and a weak basal texture. Annealing caused static dynamic recrystallization, refined the grain size and enhanced the mechanical properties: yield strength of 186 MPa, ultimate tensile strength of 304 MPa, elongation of 21% along ED. Both strength and ductility were enhanced by Al alloying.     

Microstructure and mechanical properties of Mg-6Al magnesium alloy with yttrium and neodymium

The effects of rare earth (RE) elements Y and Nd on the microstructure and mechanical properties of Mg-6Al magnesium alloy were investigated. The results show that a proper level of RE elements can obviously refine the microstructure of Mg-6Al magnesium alloys, reduce the quantity of/β-Mg17Al12 phase and form Al2Y and AI2Nd phases. The combined addition of Y and Nd dramatically enhances the tensile strength of the alloys in the temperature range of 20-175℃. When the content of RE elements is up to 1.8%, the values of tensile strength at room temperature and at 150℃ simultaneously reach their maximum of 253 MPa and 196 MPa, respectively.The main mechanisms of enhancement in the mechanical properties of Mg-6Al alloy with Y and Nd are the grain refining strengthening and the dispersion strengthening.     

喷射沉积Mg-12.55Al-3.33Zn-0.58Ca-1.0Nd合金组织与力学性能研究

利用XRD、OM、SEM、TEM研究了喷射沉积Mg-12.55Al-3.33Zn-0.58Ca-1.0Nd合金挤压态的显微组织和合金的力学性能。结果表明:喷射沉积挤压态镁合金主要包含基体α-Mg和Al2Ca相,基体组织为等轴晶,平均晶粒尺寸为3μm;Al2Ca颗粒主要沿镁基体晶界分布,颗粒尺寸在1.0μm左右,并在Al2Ca相中存在孪晶结构;合金的σb、σ0.2、δ分别为450、325MPa,5%。在拉伸断口上存在大量石块状的Al2Ca相,表明合金的断裂方式为沿晶断裂;与经热挤压的铸造AZ91镁合金对比,该合金强度明显提高,但合金塑性降低;合金强度的提高主要来源于合金的细晶强化和Al、Zn对合金的固溶强化,而伸长率降低是由于合金中存在的大量Al2Ca颗粒是沿镁基体晶界分布,导致合金的塑性降低。