钕对AZ91镁合金组织及机械性能的影响

采用微观分析、机械性能测试及断口分析等方法研究了钕对AZ91-Nd镁合金(w(Nd)=0,0.1%,0.3%,0.5%,1.0%,1.5%)的微观组织和机械性能的影响。结果表明:Nd以固溶和金属间化合物(A l11Nd3)的形式存在时具有细化晶粒、抑制二次β相析出、使不完全离异共晶转化为离异共晶的作用;Nd通过固溶强化、析出强化和细晶强化增加了合金强度和硬度,并改善了塑性;加入Nd后合金的断裂机制从脆性解理断裂转变为准解理断裂。     

热处理对反向挤压AZ80镁合金组织与性能的影响

采用光学和扫描电子显微观察、X射线衍射及拉伸试验研究了反向挤压AZ80镁合金不同热处理状态下的显微组织及性能．结果表明：反向挤压AZ80镁合金热处理后析出的β－Mg17Al12相（β相）在不同热处理状态下形貌不同．经T6热处理后,口相在晶界处呈层片状析出,与挤压态相比,合金的强度稍有降低,但延伸率明显提高;经T5热处理后,卢相在晶界处仍呈层片状,而在晶内呈颗粒状,与挤压态相比,合金的强度明显提高,但延伸率降低．     

Effect of RE on the ignition-proof, microstructure and properties of AZ91D magnesium alloy

The magnesium alloy is prone to burn during die-casting, which limits its applications severely, so the effect of adding rare earth （RE） on the ignition-proof of AZ91D Mg alloy is studied. The results indicate that the addition of mischmetal RE elements has a remarkable influence on the ignition-proof property of the magnesium alloy. It is found that the ignition temperature of the magnesium alloy can be greatly raised by adding a proper amount of RE. When the amount is 0.1wt%, the ignition temperature reaches 877℃ which is 206℃ higher than that of AZ91D without RE and the mechanical properties of the alloy are also improved, However, the amount of RE must be properly controlled because too much RE would induce grain coarsening and reduce the mechanical properties.     

Y和Ce对AZ91D镁合金显微组织和力学性能的影响

为了开发低成本、高强度、耐高温的新型镁合金,研究了微量Y、Ce对AZ91D镁合金显微组织和力学性能的影响。研究结果表明:Y和Ce复合加入AZ91D镁合金,能明显细化组织晶粒,从而改善合金在室温和高温下的力学性能。当加入0.6%Ce-0.3%Y(质量分数)时,合金晶粒细化效果较好,其室温和高温力学性能比较理想。     

Sr对Mg-5Sn-5Zn铸造镁合金组织的影响

通过光学显微镜、扫描电镜和X射线衍射仪研究了Mg-5Sn-5Zn-xSr（x=0,0.5,1,2）4种铸造镁合金的显微组织和相组成.结果表明：在Mg-5Sn-5Zn合金中加入质量分数为0.5%～2%的Sr元素后,不但能够缩小α-Mg枝晶间距,而且还能形成三元相MgSnSr.随着Sr含量的增加,在晶界析出的Mg2Sn相减少,晶内的MgSnSr相增加。合金中的MgZn相与Mg2Sn相依附在一起,大多数的MgZn相以α-Mg＋MgZn相的共晶方式存在.     

Effects of heat treatment on the microstructure and mechanical properties of ZA84 magnesium alloy

The effects of heat treatment on the microstructure and mechanical properties of ZA84 (Mg-8Zn-4Al-0.25Mn) alloy were investigated. The results indicate that the as-cast microstructure of the alloy is mainly composed of α-Mg matrix and two different morphologies of precipitates (continuous and quasi-continuous Mg32(Al,Zn)49 phases and isolated Mg5Al2Zn2 phases). After solid solution treatment at 345°C, the Mg32(Al,Zn)49 phases change from continuous and quasi-continuous net to disconnected acute angle shape,...     

Characterization of microstructure evolution and mechanical properties of the spray-deposited AZ31 magnesium alloy

The cylindrical billets of a Mg-3Al-1Zn (AZ31) alloy were synthesized by spray deposition processing. The microstruc-ture evolution and mechanical properties of the alloy were investigated. The results reveal that the microstructure of the AZ31 alloy is refined significantly by spray deposition processing. A homogeneous and equiaxial-grain structure with an average grain size of 17 μm is obtained. Further grain refinement with an average grain size of 5 μm is attributed to dynamic recrystallization during e...     

稀土元素Nd在热挤压AZ61镁合金中的作用

为了确定稀土元素Nd对热挤压AZ61镁合金显微组织和力学性能的影响，利用光学显微镜对不同含Nd量的AZ61+Nd镁合金进行了显微组织观察，并通过进行位移控制的拉伸试验测定了合金的室温和高温拉伸性能.结果表明，当热挤压AZ61+Nd镁合金中的Nd含量为0.5%时，其晶粒最细，力学性能最佳；随着Nd含量的增加，热挤压AZ61+Nd镁合金的强度有所降低，而伸长率则呈现先升高后降低的变化趋势；随着实验温度的升高，热挤压AZ61+Nd镁合金的抗拉强度和屈服强度均呈降低趋势，而伸长率则呈增加趋势.     

挤压比对AZ91镁合金组织及力学性能的影响

研究了挤压比对热挤压AZ91镁合金显微组织和拉伸性能的影响.结果表明：热挤压可以显著细化AZ91镁合金的晶粒，而且随着挤压比的增加，晶粒变得更加细小；增大挤压比也可以提高AZ91镁合金在不同实验温度下的抗拉强度和屈服强度，且经过3种挤压比挤压的AZ91镁合金在150 ℃时均呈现最高的抗拉强度和屈服强度；此外，经不同挤压比挤压的AZ91镁合金的伸长率均随实验温度的升高而增加.通过拉伸断口形貌的扫描电镜分析，确定了热挤压AZ91镁合金在室温拉伸时均表现为解理断裂为主的脆性断裂，而在较高温度下拉伸时则基本呈现韧性断裂特征.     

Si和Ca对铸态Mg-5Sn-0.5Sr合金组织和性能的影响

为了提高镁合金的耐热性能,在Mg-5Sn-0.5Sr合金中加入Si和Ca等合金化元素,设计了Mg-5Sn-0.5Sr-xSi(x=1,2)和Mg-5Sn-0.5Sr-xSi-0.5Ca(x=1,2)合金.采用x-射线衍射仪(XRD)、光学显微镜(OM)与扫描电镜(SEM)研究了合金的相组成及显微组织,并利用力学性能试验机测定了合金的拉伸性能.结果表明,Mg-5Sn-0.5Sr-xSi(x=1,2)合金组织由沿α-Mg晶界析出的共晶Mg₂Sn、Mg₂Si相与α-Mg晶内初生MgSnSr相组成,且Mg₂Si相的质量分数随Si元素的增加而增加.对于Mg-5Sn-0.5Sr-xSi-0.5Ca(x=1,2)合金而言,加入Ca元素能够显著促进初生(Ca,Sr)MgSn相的形成,而抑制晶界上Mg₂Sn相的析出.     

热挤压镁合金AZ91的微观组织及其力学行为

研究了热挤压镁合金AZ91的微观组织以及在不同试验温度和不同的热处理条件下的拉伸力学性能.结果表明：热挤压可以显著减小AZ91合金的晶粒尺寸，其拉伸力学性能与试验温度密切相关；可以通过热处理来改善其拉伸力学性能，其中人工时效及固溶时效工艺均是改善和提高挤压后AZ91镁合金力学性能的有效途径.此外，利用扫描电镜分析了AZ91镁合金拉伸试样的断口形貌，并探讨了其拉伸断裂机制.     

Using two-pass friction stir processing to produce nanocrystalline microstructure in AZ61 magnesium alloy

Despite their interesting properties,nanostructured materials have found limited use as a result of the cost of preparation and the difficulty in scaling up.Herein,a two-pass friction stir processing(FSP)technique is employed to refine grain sizes to a nanoscale.Nanocrystalline AZ61 Mg alloy with an av-erage grain size of less than 100nm was successfully obtained using FSP.Corresponding to this,the highest microhardness of the nano-grained region reached triple times that of AZ61 substrate.In prin-ciple,by ...     

热处理对挤压变形AZ61镁合金力学性能的影响

研究了几种热处理对挤压变形AZ61镁合金力学性能的影响，得出：经过固溶处理及固溶+时效处理可以使强度有所降低，但塑性提高较大，而单纯的时效处理则不能使强度降低；在挤压变形状态下，试验温度对冲击韧性的影响不大，固溶处理可以提高室温下的冲击韧性，但在低温下两者基本相同.而其它几种处理则使冲击韧性降低，并且这种冲击韧性的降低程度随着试验温度的降低而减小.     

Influence of electromagnetic stirring on microstructure of AZ91-0.8%Ce magnesium alloy

1 INTRODUCTION In recent years, magnesium alloys have been used in the automobile industry to save fuel and lower emission levels, and about 60 different types of components of magnesium alloys have been applied in automobile parts, in which AZ91magnesium alloy (Mg-Al system) approximately accounts for 90%[1?4]. It is well known that grain size has very important effect on material properties. According to Hall-Petch equation, when grain size decreases, the mechanical properties such as…     

磁场电流对AZ31镁合金组织与性能的影响

为了改善AZ31镁合金的综合性能并提高其利用价值,通过在AZ31镁合金整个凝固过程施加旋转磁场制备镁合金管坯.通过改变磁场电流对磁场与自然凝固条件下获得的AZ31镁合金铸锭的微观组织及力学性能进行了观察与测试,研究了磁场电流对AZ31镁合金显微组织和力学性能的影响.结果表明,随着磁场电流的增大,合金晶粒逐渐细化,晶粒内部出现较多的孪晶,且β-Mg17Al12相逐渐减少并细化.磁场电流越大,AZ31镁合金的力学性能越好.当磁场电流为150 A时,AZ31镁合金的抗拉强度为194 MPa,屈服强度为98 MPa,伸长率为14. 8%,与自然凝固状态相比分别提高了23. 6%、32. 4%和57. 4%.     

离心铸造对AZ91镁合金组织及力学性能的影响

为了研究卧式离心铸造工艺对AZ91镁合金力学性能及显微组织的影响,采用卧式离心铸造方法制备外径为400 mm、厚度为20 mm且长度为1 000 mm的AZ91镁合金管材,并对离心铸造态与自然凝固态AZ91镁合金管材的微观组织及力学性能分别进行了观察与测试.结果表明,离心铸造态AZ91镁合金管材的抗拉强度和伸长率分别为158 MPa和3.4%,与自然凝固态管材相比分别提高了20%和89%.离心铸造态镁合金管材的微观组织得到明显细化.与自然凝固态AZ91镁合金管材相比,离心铸造态AZ91镁合金管材在凝固过程中的共晶转变在很大程度上受到抑制,并形成了以α-Mg为主相的组织.卧式离心铸造方法提高了AZ91镁合金的综合力学性能,并使合金的组织得到细化.     

Microstructure and mechanical properties of AZ91 magnesium alloy subject to deep cryogenic treatments

AZ91 magnesium alloy was subjected to a deep cryogenic treatment. X-ray diffraction （XRD）, scanning electronic microscopy （SEM）, and transmission electronic microscopy （TEM） methods were utilized to characterize the composition and microstructure of the treated samples. The results show that after two cryogenic treatments, the quantity of the precipitate hardening β phase increases, and the sizes of the precipitates are refined from 8-10μm to 2-4μm. This is expected to be due to the decreased solubility of aluminum in the matrix at low temperature and the significant plastic deformation owing to internal differences in thermal contraction between phases and grains. The polycrystalline matrix is also noticeably refined, with the sizes of the subsequent nanocrystalline grains in the range of 50-100 nm. High density dislocations are observed to pile up at the grain boundaries, inducing the dynamic recrystallization of the microstructure, leading to the generation of a nanocrystalline grain structure. After two deep cryogenic treatments, the tensile strength and elongation are found to be substantially increased, rising from 243 MPa and 4.4% of as-cast state to 299 MPa and 5.1%.     

Semisolid die forging process,microstructures and properties of AZ31 magnesium alloy mobile telephone shells

A semisolid slurry of AZ31 magnesium alloy was prepared by vibrating wavelike sloping plate process,and the semisolid die forging process,microstructures,and properties of the magnesium alloy mobile telephone shell were investigated.The semisolid forging process was performed on a YA32-315 four-column universal hydraulic press.The microstructures were observed by optical microscopy,the hardness was analyzed with a model 450SVD Vickers hardometer,the mechanical properties was measured with a CMT5105 tensile ...