挤压态Mg-10Gd-3Y-0.5Zr镁合金的低温力学性能(英文)

研究多循环低温交变(液氮浸泡处理)和拉伸温度对挤压态Mg10Gd3Y0.5Zr镁合金的微观组织、力学性能以及断裂机制的影响。结果表明,Mg10Gd3Y0.5Zr合金经10d液氮浸泡或10个周期高低温交变循环后,合金室温力学性能基本不变;而经过20个周期高低温循环后,合金的室温抗拉强度由398MPa升高到417MPa。在196°C下拉伸时,挤压态Mg10Gd3Y0.5Zr镁合金的屈服强度和抗拉强度均大幅度提高,分别为349MPa和506MPa,分别增长了18%和27%。合金室温断裂机制为穿晶解理断裂,而低温条件下为韧性断裂和解理断裂并存的混合断裂机制。     

Microstructure and mechanical properties of rolled Mg-12Gd-3Y-0.4Zr alloy sheets

The extruded Mg-12Gd-3Y-0.4Zr alloy sheets were rolled from 30 mm to 2.3 mm at 723 K by electric heated rollers,and then different heat treatments were performed to improve their properties.The microstructures and tensile properties of the alloy sheets were investigated,including as-rolled,annealed and T5 treated.The experimental results show that the grains are effectively refined by the rolling process,and the strength of the rolled alloy is greatly enhanced.The annealed alloy exhibits lower strength a...     

Influence of heat treatment on microstructure and mechanical properties of Mg-10Gd-3Y-1.2Zn-0.4Zr alloy

Microstructure evolution and mechanical properties of the cast Mg-10Gd-3Y-1.2Zn-0.4Zr(mass fraction,%) alloy during annealing at 798 K for different time were investigated.In the as-cast state,the microstructure consists ofα-Mg,Mg_5(Gd,Y,Zn) eutectic compounds and stacking faults(SF) of basal plane distributed from grain boundary to inner grain.During heat treatment at 798 K,the SF and parts of eutectic compounds dissolve into the matrix gradually,simultaneously,a new straight lamellar phase with 14H typ...     

热处理对砂型铸造Mg-10Gd-3Y-0．5Zr镁合金微观组织和力学性能的影响

采用金相分析、SEM、硬度试验和拉伸试验等方法分析和测试砂型铸造 Mg-10Gd-3Y-0.5Zr 镁合金在T6态（固溶后空冷然后时效）下的显微组织和室温力学性能,讨论该合金的断裂机理。结果表明,砂铸Mg-10Gd-3Y-0.5Zr合金在225℃和250℃时效下的最优T6热处理工艺分别为（525℃,12 h＋225℃,14 h）和（525℃,12 h＋250℃,12 h）。峰时效下T6态Mg-10Gd-3Y-0.5Zr合金主要由α-Mg＋γ＋β′相组成,2种峰时效热处理工艺下合金的抗拉强度、屈服强度和伸长率分别为339.9 MPa、251.6 MPa、1.5%及359.6 MPa、247.3 MPa、2.7%。在不同热处理工艺下Mg-10Gd-3Y-0.5Zr合金断裂的类型不同,峰时效态合金的断裂方式为穿晶准解理断裂。     

挤压变形对Mg-5.0Y-7.0Gd-1.3Nd-0.5Zr合金组织和性能的影响

对Mg-5.0Y-7.0Gd-1.3Nd-0.5Zr(EW75M)合金在不同条件下挤压变形后的组织和性能进行测试。结果表明:随着挤压比的增大,合金的强度和塑性均大幅度提高,当挤压比增大到20以后,晶粒细化对合金的强化效果趋于稳定;当挤压筒温度由400℃升高到450℃时,合金强度和伸长率的降幅均在5%以内,挤压筒温度在400℃~450℃变化时对合金挤压变形后的性能影响较小;将合金均匀化处理(535℃、24h)后直接进行挤压变形(挤压比20,挤压筒温度400℃,挤压速度1~2m/min),其极限抗拉强度、屈服强度和伸长率分别达到335MPa、240MPa和16.5%。     

真空压铸Mg-6Gd-3Y-0.5Zr镁合金的组织与性能

采用真空压铸工艺制备GW63K合金,研究压射速度和真空度对组织及性能的影响。采用光学显微镜、SEM及EDX对组织进行观察。研究GW63K的热处理工艺。结果表明：铸态GW63K合金由α-Mg基体和Mg24（Gd,Y）5第二相组成,且随着压射速度的增加,合金的屈服强度没有大的变化,但是伸长率先增加后减小;真空辅助能够减少气孔的大小及含量。在475℃固溶2 h,然后在200℃下时效80 h,GW63K合金的抗拉强度和伸长率分别达到308 MPa和9.45%。首次发现预初晶（ESCs）的存在对压铸GW63K合金热处理性能有巨大影响,预初晶（ESCs）的存在严重降低热处理后合金的性能。     

不同固溶状态Mg-10Gd-3Y-1.2Zn-0.5Zr合金的力学性能及断裂行为研究

通过在Mg-10Gd-3Y-0.5Zr合金中添加少量Zn制备出一种新型Mg-10Gd-3Y-1.2Zn-0.5Zr合金,并利用扫描电子显微镜、拉伸试验机分析研究Mg合金不同状态下的显微组织、力学性能及断裂行为。结果表明：Mg-10Gd-3Y-1.2Zn -0.5Zr合金在不同的时效状态下,铸态塑性差,T4态塑性好,T6态塑性优于铸态但劣于T4态,且所有样品都是脆性解理断裂为主,晶界和层状相界面比化合物界面结合牢固。通过比较3个不同温度下T6态的力学性能,发现提高固溶温度能提高合金的强度,但延伸率会略降。并且Zn促进层状相生长,但是对基体塑性提高作用有限。     

Sm对时效态Mg-12Gd-2Y-0.5Zr合金组织与力学性能的影响

通过组织观察、拉伸试验和断口分析,研究了Mg-12Gd-2Y-（0,0.5,1.0,1.5）Sm-0.5Zr合金的显微组织和20～300℃下的力学性能。结果表明,随着Sm含量的增加,合金晶粒细化,屈服强度及高温抗拉强度显著提高。同时,随着温度的升高,合金的抗拉强度具有反常的温度效应。     

二次挤压对Mg-12Gd-3Y-0.6Zr合金显微组织及力学性能的影响

利用光学显微镜、扫描电子显微镜、X射线衍射仪等研究二次挤压对Mg-12Gd-3Y-0.6Zr合金显微组织及力学性能的影响。研究表明:该合金经二次挤压后,晶粒尺寸细化至6μm,提高细晶强化效果;粗大Mg5Gd1-xYx相增多,降低固溶强化效果;{0002}基面织构的减弱降低织构强化效果;在三者的综合作用下,合金经二次挤压后,强度有所降低,但伸长率却大幅度提高,达到20.5%,较一次挤压态合金的伸长率提高107.1%;一次挤压态合金的断裂方式是以解理断裂为主的混合断裂,二次挤压态合金的断裂方式为韧性断裂。     

Zn元素对Mg-7Y-3Sm-0.5Zr合金显微组织和力学性能的影响(英文)

研究添加Zn元素对铸造Mg-7Y-3Sm-0.5Zr合金的显微观组织和力学性能的影响。蠕变测试的温度范围为200-300 °C,应力范围为50-120 MPa。在本研究的蠕变测试条件下,合金的蠕变激活能为156-221kJ/mol。采用光学显微镜、扫描电镜和透射电镜观察合金在蠕变过程中显微组织的演化。结果表明:尽管合金在250 °C以下有着相似的蠕变行为,仅添加1%的Zn元素就能使合金在300 °C和50MPa蠕变条件下的蠕变寿命从52.2h提高到152.8h,表明Zn元素能够提高合金的高温抗蠕变性能。加入Zn元素后,合金中形成的高温稳定相和片层状结构相是合金高温抗蠕变性能提高的根本原因。     

Mg-9Gd-4Y-0.6Mn合金的微观组织与力学性能

通过热分析、X射线衍射、扫描电镜、透射电镜等手段分析了Mg-9Gd-4Y-0.6Mn合金的微观组织,并在室温到400℃的温度区间进行力学拉伸试验.结果表明合金在400℃时产生的超塑性现象,伸长率达266%,拉伸过程中出现动态再结晶协调晶界滑移的超塑性变形机制;在凝固过程中合金易偏析形成Mg3X(X为Gd和Y)相,Mg3X相用固溶处理的方法难以消除;在Cast-T5、Cast-T6、Rolled-T5和Rolled-T6的四种热处理状态中,Rolled-TS态的硬度最高,达121HV10;沿棱柱面析出的高密度板状析出相能有效地阻碍镁基面上的位错滑移,这是合金强化和耐热的主要原因.     

Mechanical properties of Mg-9Gd-4Y-0.6Zr alloy

The microstructures and mechanical properties of Mg-9Gd-4Y-0.6Zr alloy were investigated. The results show that the ultimate tensile strengths of the extrusion-T5 temper of this alloy at -196, 25,250, 300 and 350℃ are as high as 521,370, 348, 262 and 150 MPa, respectively. It is noteworthy that 8% plasticity occurs at -196 ℃ and 180% superplasticity occurs at 400℃. In the peak hardness of Cast-T5, Cast-T6, Ext-T5 and Ext-T6, the highest is that of Ext-T5. The prismatic precipitates providing an effective barrier to dislocation gliding on the basal plane are the cause of strengthening of this alloy. The plate-shaped precipitates formed on the prismatic planes provide the most effective barriers to the gliding dislocations, and they are the cause of strengthening of this alloy.     

Ho对铸态Mg-5Y-3Sm-0.5Zr合金显微组织和力学性能的影响

采用光学显微镜、扫描电镜、X射线衍射仪、电子拉伸实验机、布氏硬度计等研究了铸态Mg-5Y-3Sm-xHo-0.5Zr(x=0,2,4,6)合金的组织和力学性能。结果表明:铸态Mg-5Y-3Sm-0.5Zr合金主要由α-Mg和大部分位于晶界的Mg24Y5和Mg41Sm5第二相组成。添加Ho后,在晶界处出现了Mg24Ho5新相,Ho的含量高低对合金相组成没有影响。随着Ho含量的不断提高,析出的第二相逐渐增多,晶粒尺寸逐渐减小。当Ho含量为4%时,该铸态合金的综合力学性能最好,抗拉强度、屈服强度、硬度和伸长率分别为193 MPa、170 MPa、72.8 HBW和4.15%。     

挤压Mg-8.5Gd-2.3Y-1.8Ag-0.4Zr合金的显微组织与力学性能(英文)

研究铸态和挤压态Mg-8.5Gd-2.3Y-1.8Ag-0.4Zr合金的显微组织、时效强化和力学性能。铸锭在T4处理后分别于400、450和500°C进行挤压,挤压比为10:1。在细晶强化和析出强化的共同作用下,于400°C挤压的样品经T5处理后可以得到最优的力学性能,所得的晶粒尺寸约为5.0μm,其初始和峰值硬度分别为HV109和HV129。室温下的拉伸屈服强度、抗拉强度和伸长率分别达到391MPa、430MPa和5.2%。     

热处理对Mg-8Gd-3Y-1.5Zn-0.6Zr合金组织与力学性能的影响

采用光学显微镜(OM)、扫描电镜(SEM)、X射线衍射仪和万能力学试验机等研究了固溶和时效处理对Mg-8Gd-3Y-1.5Zn-0.6Zr合金显微组织和力学性能的影响。结果表明,Mg-8Gd-3Y-1.5Zn-0.6Zr合金铸态、固溶态和时效态的显微组织均由α-Mg基体、Mg₅(Gd, Y, Zn)相和LPSO结构组成;合金经固溶和时效处理后的最大抗拉强度由铸态的187.96 MPa提高到241.93 MPa,提高了28.71%,伸长率由铸态的8.48%提高到13.91%,提高了64.03%;不同热处理状态下合金的拉伸断口形貌主要以脆性断裂为主。     

Effects of second phases on fracture behavior of Mg-10Gd-3Y-0.6Zr alloy

The effects of second phases on the fracture behavior of Mg-10Gd-3Y-0.6Zr alloy were investigated. The results show that the fracture mode can be generally described as ductile transgranular fracture in as-extruded condition and intergranular fracture in peak-aged condition. In as-extruded condition, the ductile transgranular fracture occurs by the formation and transgranular propagation of the microcrack from the broken primary phases. However, as the collaboration effects of precipitates inside grains and on the grain boundaries have the tendency to reduce the cohesive strength of the grain boundary, and make the grain boundaries the favorable path for crack propagation, the intergranular fracture occurs in peak-aged condition.     

Influence of GdCl3 addition on purifying effectiveness and properties of Mg-10Gd-3Y-0.5Zr alloy

In order to improve the purifying efficiency of R J6 flux, 5% （mass fraction） GdCl3 was introduced into the flux for refining Mg-10Gd-3Y-0.5Zr （GW103K） alloy. The results show that the RJ6 flux containing 5% GdCl3 exhibits better adsorption ability to nonmetallic inclusions than the one without GdCl3. Moreover, the mechanical, corrosion properties and fluidity of the alloy refined with RJ6 flux and RJ6 flux containing 5% GdCl3 were investigated, respectively. It is found that these properties are improved to a certain degree due to the removal of nonmetallic inclusions in the alloy. Thermodynamic analysis and surface tension experiments indicate that the main reason can be ascribed to the decrease of the surface tension of the flux with 5% GdCl3, which promotes the combination of flux and nonmetallic inclusions.     

Mg-13Gd-3Y-0.4Zr合金热处理工艺优化及其性能

为了开发高强度高温耐热镁合金,制备了Mg-13Gd-3Y-0.4Zr(GW133K)合金,并测试了其常温力学性能和蠕变性能,测得此合金在优化后屈服强度达到了275MP,抗拉强度为300MP,在250℃-80MP条件下,100小时蠕变应变率为1.18%,稳态蠕变速率为3.61e-9,并对此合金的增强机制进行了探讨。     

Influence of extrusion temperature on microstructure and mechanical properties of Mg-4Y-4Sm-0.5Zr alloy

The solution-treated Mg-4Y-4Sm-0.5Zr alloy was extruded at temperatures from 325℃ to 500℃.Dynamic recrystallization(DRX) completely occurs when the alloy is extruded at 350℃and above.The grains of the extruded alloy are obviously refined by the occurrence of DRX.The average grain size of the extruded alloy increases with increasing the extrusion temperature,leading to a slight decrease of the ultimate tensile strength(UTS) and the yield strength(YS) .On the contrary,the UTS and YS of the extruded and aged alloy increase with increasing the extrusion temperature.Values of UTS of 400 MPa,YS larger than 300 MPa and elongation(EL) of 7%are achieved after extrusion at 400℃ and ageing at 200℃ for 16 h.Both grain refinement and precipitation are efficient strengthening mechanisms for the Mg-4Y-4Sm-0.5Zr alloy.     

热处理工艺对高真空压铸Mg–8Gd–3Y–0.4Zr镁合金组织及力学性能的影响

研究T4和T6热处理状态下高真空压铸Mg-8Gd-3Y-0.4Zr（质量分数,%）合金的微观组织、化合物含量、力学性能及断裂行为。铸态Mg-8Gd-3Y-0.4Zr合金微观组织主要由α-Mg和共晶Mg24（Gd,Y）5化合物组成。经固溶处理后,共晶化合物大量溶解于镁基体,合金主要含过饱和α-Mg及方块相。固溶合金中方块相的含量随固溶温度的升高而增大,力学性能也有所提高。根据微观组织结果,确定475℃,2 h为Mg-8Gd-3Y-0.4Zr合金最优固溶方案。合金的最佳屈服强度为222.1 MPa,延伸率可达15.4%。铸态,T4状态下和T6状态下合金的拉伸断裂模式为穿晶准解理断裂。