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1.
对AZ91D镁合金进行了半固态等温热处理,通过光学显微镜、扫描电镜对其组织进行了研究。结果表明,AZ91D镁合金铸件经过580℃×30min半固态等温热处理后,合金显微组织中β-Mg17Al12相基本熔入基体,枝晶状的铸态组织在等温处理过程中变得细小圆整。  相似文献   

2.
借助于金相显微镜研究了MgCo3对AM60B镁合金铸态显微组织和固溶组织的影响。结果表明,MgCO3对AM60B镬合金具有明显的细化作用,加入1.2%的MgCO3使得AM60B镁舍金的二次枝晶臂同距与晶粒尺寸显著减小.由粗大的树枝晶变为细小均匀的等轴晶,进一步增加MgCO3的含量,合金组织反而有粗化倾向。  相似文献   

3.
利用低温浇注与晶粒细化法制备了半固态A356铝合金坯料,研究了在细化剂作用下等温热处理工艺条件对其组织的影响规律.研究结果表明,稀土细化剂的加入对试样等温热处理前的铸态组织和热处理后的加热组织都有明显的改善作用,且稀土细化及低温浇注共同作用时,所获得的半固态非枝晶A356铝合金试样等温热处理最佳工艺条件为583℃下保温30 min,此时坯料触变性良好,其晶粒平均圆度达到0.83,晶粒平均等积圆直径达到80μm.  相似文献   

4.
本文详细论述了半固态非枝晶组织合金制备技术的基本原理与特点,介绍了半固态非枝晶组织合金制备技术的现状与发展概况,并展望了半固态非枝晶组织合金的应用前景。  相似文献   

5.
半固态加工技术在镁合金零部件生产中的应用   总被引:2,自引:0,他引:2  
镁合金由于其具有低密度、高的比强度和比刚度、良好的导电导热性和电磁屏蔽性而日益受到工业界的瞩目。采用半固态加工技术生产的镁合金零部件,精度高、质量好,可与近终形加工技术相衔接等特点,同时可以消除传统压铸方法生产镁合金零件所产生的气孔、缩松等缺陷,已在日本和台湾的电子产业中得到应用。本文主要介绍已开发成功、适用于镁合金的半固态浆料制备方法,其中包括搅拌法、半固态等温热处理法、浇注温度控制法、化学晶粒细化法等,探讨工艺因素对半固态浆料组织的影响,同时介绍镁合金半固态成形的主要方法-注射成形技术,最后对镁合金的半固态加工技术做了展望。  相似文献   

6.
针对镁合金对半固态成形工艺是否适应的问题,借助计算机辅助热分析方法,定量解析了AM60和AZ91D两种镁合金固相率与温度的关系,并据此分析讨论了这两种镁合金的半固态成形性。结果表明,AM60镁合金不宜采用半固态流变成形工艺,而应采用半固态触变成形工艺,其初始固相率为62%,工艺窗口为56.2℃;AZ91D镁合金既适应半固态流变成形工艺,又适应半固态触变成形工艺。当采用半固态流变成形工艺时,其最佳初始固相率为40%,工艺窗口大小为15.4℃;当采用半固态触变成形工艺时,其最佳固相率为60%,工艺窗口大小为23.2℃。  相似文献   

7.
半固态金属加工是近年来金属加工技术研究的热点.论述了半固态合金非枝晶组织制备方法,如:机械搅拌法、电磁搅拌法、紊流效应法、剪切一冷却一滚动法、应变诱发熔化激活法、喷射沉积法等.介绍了近些年来半固态合金非枝晶组织机理研究的新进展,并提出了今后的研究方向.  相似文献   

8.
本文对经Al-5Ti-0.25C细化的Mg-15Al合金进行半固态等温处理;研究了细化效果、等温温度、保温时间对含铝15%镁合金半固态浆料组织的影响。结果表明:熔体温度790℃时加入0.8%的Al-5Ti-0.25C,该合金细化效果最好;在540℃进行半固态等温处理90min,得到细小圆整均匀的半固态球状组织。  相似文献   

9.
研究了AZ91D合金在半固态等温热处理过程中,等温温度和等温时间对其组织和力学性能的影响.结果表明:在本实验条件下,当等温热处理温度为585℃、等温时间90min时,AZ91D合金具有良好的组织形态和力学性能.  相似文献   

10.
一种新型镁合金的开发及其应用   总被引:2,自引:0,他引:2  
在商用AM60B镁合金的基础上,开发了新型的Mg-6Al-0.3Mn-xRE系合金(x=0.4、0.8、1.2、1.6、2.0wt%),并系统研究其组织、力学性能、断裂机制、铸造性能、热处理工艺,寻找最优化的合金成分和热处理工艺。采和Mg-6Al-0.3Mn-1.6RE合金成功地试制了国内第一批镁合金汽车轮毂样品,探索了汽车轮毂的表面处理工艺。  相似文献   

11.
对预变形后的Al-25%Si合金进行半固态等温处理,研究了半固态等温处理工艺参数对合金组织的影响。利用光学显微镜观察组织,Image Pro Plus金相分析软件来测定初生硅平均直径和形状因子。结果表明,挤压变形后初生硅相的尺寸有明显的细化,但形态较差,而通过半固态等温处理后初生硅的颗粒得到明显的球化,但其平均直径有所增加。  相似文献   

12.
铝合金等温半固态触变成形是一种先进的成形工艺理念,目前尚处于工程化应用前期。本文以AlMg_5Si_2Mn铝合金为研究对象,采用等温热处理法制备实验合金半固态浆料,并研究其半固态等温过程的组织演变规律。然后使用压铸设备开展AlMg_5Si_2Mn铝合金的半固态成形工艺试验,探索可行的半固态成形工艺和合理实现路径。  相似文献   

13.
Semi-solid AZ91D magnesium alloy was investigated in isothermal steady-state condition. The influence of stirring technological parameters such as stirring temperature and shear rate to apparent viscosity of semi-solid alloy slurry was discussed. Apparent viscosity increases with stirring temperature decreases at the same shear rate. At the same stirring temperature, apparent viscosity decreases rapidly at first with shear rate increases, and then apparent viscosity decreases slowly with shear rate increases, when shear rate reaches a certain value, apparent viscosity appears tiny increase. According to the experimental data, the relation between solid volume fraction and apparent viscosity of semi-solid AZ9l D alloy at shear rate 238 s- 1 is fitted by regression method, it supplies useful data to the numerical simulation of semi-solid AZ91D alloy die casting process.  相似文献   

14.
Friction and Wear Characteristics of Mg-Al Alloy Containing Rare Earths   总被引:7,自引:4,他引:3  
The influence of rare earth on the friction and wear characteristics of magnesium alloy AZ91 and AM60 were studied. The results show that the wear resistance properties of rare earth magnesium alloys are better than those of matrix alloy under the testing conditions. The anti-wear behaviour of AZ91 alloy is much better than that of AM60 alloy. In dry sliding pmcess, magnesium alloys undergo a transition from mild wear to severe wear. The addition of rare earths refine the structure of alloys, improve the comprehensive behaviors of magnesium alloys,increase the stability of oxidation films on worn surfaces,enhance the loading ability of rare earth magnesium alloys,and delay the transition from mild wear to sevre wear effectively.  相似文献   

15.
热加工对铸造AM50镁合金显微结构和力学性能的影响   总被引:4,自引:0,他引:4  
采用锻造和等通道转角挤压(ECAP)等技术研究了热加工对铸造AM50镁合金显微结构和力学性能的影响, 以改善该合金的力学性能.结果发现, ECAP对铸造AM50镁合金和锻造AM50镁合金两种显微结构的影响不同, 这是由于两种状态初始晶粒尺寸不同引起的.铸态AM50镁合金晶粒尺寸粗大, 经过ECAP工艺后, 晶界上出现大量平直滑移线;而锻态AM50镁合金经过ECAP工艺后, 晶粒进一步细化, 滑移线痕迹不明显.铸态AM50镁合金经过ECAP工艺后显微硬度从54.5提高到72.3, 锻造AM50镁合金经过ECAP工艺后显微硬度从60.3提高到81.9.铸造AM50镁合金经过锻造及ECAP工艺热加工后力学性能抗拉强度提高到320 Mpa, 同时延伸率保持在35%以上.  相似文献   

16.
In order to improve the corrosion and mechanical properties of AM50 magnesium alloy, 1 wt.% Gd was used to modify the AM50 magnesium alloy. The microstructure, corrosion and mechanical properties were evaluated by X-ray diffraction(XRD), scanning electron microscopy(SEM), energy dispersive spectroscopy(EDS), electrochemical and mechanical stretch methods. The results indicated that β-Mg17Al12 phase decreased and Al2Gd3 and Al0.4GdMn1.6 phase existed after Gd addition. Because of the Gd addition, the grain of AM50 magnesium alloy was refined significantly, which improved the tensile strength of AM50 magnesium alloy. The decreasing of β phase improved the corrosion resistance of the magnesium alloy. The fracture mechanism of the Gd modified AM50 magnesium alloy was quasi-cleavage fracture. The corrosion residual strength(CRS) of AM50 magnesium alloy was improved after 1 wt.% Gd addition.  相似文献   

17.
An attempt has been made to understand the microstructural evolution during semi-solid isothermal holding of liquidus cast Sr-modified A356 alloy. It was observed that the liquidus casting is effective in producing non-dendritic microstructure with average sphericity of 0.8 and 0.82 for unmodified and modified alloys, respectively. Isothermal holding of the samples at a temperature corresponding to solid fraction of 0.3 for 15 min enhanced the sphericity of unmodified and modified alloys to 0.84 and 0.85, respectively. Further increase in holding resulted grain coarsening and reduction in sphericity. The grain coarsening rate (K) of samples was analysed with Lifshitz–Slyozov–Wanger equation, and the values of K were found to be 58.3 and 98.3 µm3/s for unmodified and modified alloys, respectively. The grain coarsening in unmodified alloy was dominated by Ostwald ripening, whereas in case of modified alloy, grain coarsening was governed by grain coalescence.  相似文献   

18.
For thixoforming to be possible,the microstructure of the starting material must be non-dendritic,which can be obtained by the strain induced melt activation(SIMA)route.Based on the SIMA route,as-cast AZ91D alloy with the addition of yttrium was deformed by cyclic closed-die forging(CCDF).Microstructure evolution of CCDF formed AZ91D-RE alloy during partial remelting were investigated.Furthermore,the mechanical properties of thixoformed AZ91D-RE magnesium alloy components were also studied.The results showed that prolonged holding time resulted in grain coarsening and the improvement in degree of spheroidization.The coarsening behaviour of solid grains in the semi-solid state obeyed Ostwald ripening mechanism.The coarsening rate constant of CCDF formed AZ91D-RE during partial remelting was 324 um3/s at 550℃.The value of yield strength,ultimate tensile strength and elongation to fracture of four-pass CCDF formed AZ91D-RE magnesium alloy were 214.9,290.5 MPa and 14%,respectively.Then the four-pass CCDF formed alloys were used for thixoforming.After holding at 550℃ for 5 min,the values of yield strength,ultimate tensile strength and elongation to fracture of thixoformed component were 189.6 MPa,274.6 MPa and 12%,respectively.However,prolonged holding time led to remarkable decrease in mechanical properties of thixoformed components.  相似文献   

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