热加工对铸造AM50镁合金显微结构和力学性能的影响

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.     

钇对Ti-43Al-9V合金组织性能的影响

采用OM，XRD，SEM和TEM等测试方法，分析了稀土元素(Y)对Ti—43Al—9V合金显微组织以及力学形能的影响。实验结果表明，Ti—43Al—9V—0．3Y合金由γ相、α2相、B2相和YAl2相组成；添加稀土可以细化Ti—43Al—9V合金的晶粒尺寸，并促进细小的α2／γ层片形成以及细化粗大的α2／γ／B2层片。对TiAl合金力学性能测试表明，适量添加稀土Y(0．3％，原子分数)可明显改善合金的室温强度和塑性，但过量添加将会造成材料性能降低；断口分析表明过量添加稀土导致沿晶断裂比例增加将损害TiAl合金的性能。     

Influences of Yttrium on Microstructure and Mechanical Properties of NiAl-28Cr-5.5Mo-0.5Hf Alloy

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Al-Ti-B对AZ91D镁合金显微组织和力学性能的影响

研究了Al-Ti-B对AZ91D镁合金铸态显微组织和力学性能的影响，并探讨其化学成分与组织结构和力学性能之间的变化。研究结果表明：Al-Ti-B加入AZ91D镁合金，能明显细化组织晶粒，从而改善合金的室温力学性能。当加入Al-Ti-B时，合金晶粒细化效果较好，其室温力学性能和硬度比原来都有较大的提高。     

Effect of Neodymium on Microstructure and Mechanical Properties of Mg-Sb Alloy

The effects of Nd on the microstructure and mechanical properties of Mg-Sb3 alloy were studied with the 0～0.15% addition content. The addition of Nd makes the grain of Mg-Sb3 alloy obviously refined, where the grain size decreases from 100～200 μm to 0.2～10 μm. And the typical dendrite characteristic turns into the equiaxed grain microstructure with the addition of 0.05%～0.1% Nd. The reason for grain refinement is from the supercooling theory. The mechanical properties tested indicate that the tensile strength and especially elongation of the alloys are improved with the addition of Nd and their maximum enhancing rates based on the Nd-free Mg-Sb3 alloy are 20% and 10% at 0.1% Nd, respectively. The main reason is attributed to the grain refinement by Nd. The tensile strength and especially elongation decline when Nd addition is over 0.1%, owing to the number and size increase of the needle-shaped phases on the grain boundaries with the Nd addition increasing.     

铈对铸造镁合金AZ91D显微组织与力学性能的影响

利用光学金相显微镜OM和XRD分析了分别加入0．1％，0．3％，0．5％，0．7％和1．0％Ce的AZ91D合金显微组织和相组成，测试了室温力学性能和硬度。结果表明，加入一定量Ce后的AZ91D合金形成杆状化合物Al4Ce，被推移到生长界面，阻碍枝晶的自由生长，从而细化合金显微组织；Ce能提高AZ91D合金室温抗拉强度和硬度，而对其屈服强度和延伸率影响不大；加入0．7％Ce的AZ91D合金晶粒细化效果好，其综合力学性能比较理想。     

Effect of Neodymium on As-Cast Microstructure and Mechanical Properties of AZ31 Wrought Alloy

Nd in the form of powder or intermediate alloy was added to AZ31 wrought alloy. The as-obtained alloy was characterized and tested with respect to its microstructure and mechanical properties. The relationship between the microstructure, mechanical properties and tensile fracture mechanism were discussed, with relevant alloys as reference for comparison. Experimental results show that the same quantity of Nd was added into AZ31 in powder form or in intermediate alloy, the absorption rate of Nd reached only 10.8% for the former case and as high as 95% for the later case. Pure Nd powder was added, no new compound was detected, but it served as reductant and purified alloy melt, resulting in improving the tensile strength while Nd was added into AZ31 as Mg-Nd intermediate alloy. The compound Al2Nd and Mg12 Nd were formed in magnesium alloy, which were distributed in the matrix in the shapes of strip and particle, evidently refined the as-cast structure. The as-cast tensile strength (228MPa) of adding pure Nd powder approximated to the figure (245MPa) of adding Mg-Nd intermediate alloy. The tensile fracture mchanism of as-cast AZ31 transformed from cleavage fracture into quasi-cleavage fracture.     

Effect of ErCl3 Addition on Microstructures and Properties of AZ91 Magnesium Alloy

Effect of ErCl_3 Addition on Microstructures and Properties of AZ91 Magnesium Alloy     

钇对2519铝合金的组织与性能的影响

用X射线、光学显微镜及扫描电镜等研究了钇对2519铝合金的组织及力学性能的影响,实验结果表明:加入适量钇(0.1%质量分数)后,合金的强度、硬度、伸长率提高,合金的再结晶组织细化,当钇含量超过0.1%时,合金的强度、硬度、伸长率随钇含量的增加而逐渐降低,适宜的含钇量为0.1%,钇主要以Al6Cu6Y化合物的形式存在并沿晶界分布。     

Mechanism of Effects of Rare Earths on Microstructure and Properties at Elevated Temperatures of AZ91 Magnesium Alloy

By using real-space recursion method,the energetics of the undoped and Al and/or RE atoms doped 7（1450）〈0001〉 symmetric tilt grain boundaries（GBs）in AZ91 alloys were investigated.Similar calculations were performed on undoped and doped bulk α Mg for comparison.The results showed that Al atoms segregated at GBs in AZ91 alloys.When RE atoms were added,they also segregated at GBs,and their segregation is stronger than Al atoms＇.Therefore,RE atoms retard the segregation of Al atoms.Calculations of interaction energy indicated that Al atoms repelled each other,and could form ordered phase with host Mg atoms.On the contrary to the case of Al,RE atoms attracted each other,they could not form ordered phase with Mg,but could form clusters.Between RE and Al,there existed attractive interaction,and this attractive interaction was the origin of Al11RE3 precipitation.Precipitation of Al11RE3 particles with high melting point and high thermal stability along GB improves high temperature properties of AZ91 alloys.     

Effects of RE on Microstructures and Mechanical Properties of Hot-Extruded AZ31 Magnesium Alloy

Effects of rare earth (RE) additions on microstructure and mechanical properties of the wrought AZ31 magnesium alloy were investigated. The results show that, by adding 0.3%, 0.6% and 1.0% RE elements, the as-cast microstructure can be refined, and the as-cast alloys‘ elongation and tensile strength can be improved. After extrusion, the alloy with 0.3 % and 0.6% RE additions obtain a finer microstructure and the best mechanical properties, but the alloy with 1.0% RE addition has the coarse A1-RE compound particles in grain boundaries which decreased elongation and tensile properties. Usually, Rare earth (RE) elements were used to improve the creep properties of aluminium-containing magnesium pressure die cast alloys at elevated temperatures. In this paper, it is also found that the high temperature strength of extruded materials can be increased by RE elements additions.     

稀土元素Sm对Mg-Zn-Y合金组织结构和力学性能的影响

制备了Mg-6Zn-1.5Y-0.8Zr-xSm(x=0,1,2,3)系列合金,研究了稀土元素Sm对Mg-6Zn-1.5Y-0.8Zr合金组织结构和力学性能的影响.通过金相显微镜、扫描电镜、EDS、XRD等观察和分析了合金的微观形貌和组织结构,测量了合金抗拉强度、屈服强度和伸长率等力学性能.结果表明:合金中添加稀土元素Sm后晶粒有了明显的细化,随着Sm元素含量的增加,晶粒细化效果更为明显;通过XRD分析,添加Sm元素后,合金中并没有出现新的含Sm的物相,通过扫描电镜和EDS分析表明,合金中加入的Sm置换了部分Y,形成了Mg3( SmY)2 Zn3,Mg3( SmY) Zn6的相结构,Sm元素对Y的置换主要出现在Mg3( SmY) Zn6结构当中,在Mg3 (SmY) Zn6相结构出现较少;力学性能测试结果表明,随着Sm含量增多,合金晶粒细化,细晶强化作用明显,合金屈服强度逐渐增大,而抗拉强度和伸长率在Sm含量为2％时达到最大,比未添加Sm元素时提高约15％以上.     

Study on Ignition Proof AZ91D Magnesium Alloy Chips with Cerium Addition

The effect of Ce on ignition point of AZ91D magnesium alloy chips was studied. For the AZ91D and the AZ91D-xCe magnesium alloys, changing the sizes of the chips in the range of 58 - 270 μm has a limited influence on ignition point, however, the shift of the content of Ce has much effect on ignition point. Increasing the Ce content, x from 0.15 to 0.25, the ignition point increases with increasing of Ce; however, x from 0.25 to 0.45, the ignition point decreases with increasing of Ce. By the addition of Ce of 0.25 %. the ignition point is raised by 43℃.     

稀土元素铈对镁合金AZ91D显微组织和力学性能的影响

利用光学显微镜、X射线衍射和扫描电镜等分析研究含铈镁合金AZ91D（0．25％Ce、0．7％Ce、0．95％Ce）的显微组织,并对其力学性能进行了测试,同时与不含铈镁合金AZ91D进行了比较。结果表明,加入一定量Ce后的镁合金AZ91D形成杆状化合物Al4Ce,被推移到生长界面,阻碍枝晶的自由生长,从而细化合金显微组织;Ce能提高镁合金AZ91D抗拉强度和硬度,而对其屈服强度和延伸率影响不大;加入0．7％Ce的AZ91D镁合金晶粒细化效果和综合力学性能比较理想。     

超声处理对AZ80镁合金组织与性能的影响

通过OM、SEM及阿基米德法等手段,研究超声处理对AZ80镁合金凝固组织、密度和力学性能的影响。结果表明:610℃超声处理可以降低晶粒尺寸,减少枝晶数量。经过超声处理后,合金密度由1.770g/cm3升至1.805g/cm3,抗拉强度由138MPa升高到170.5MPa,延伸率由2.5%提高为4.0%。     

钇对AZ91合金组织和性能的影响

研究微量稀土钇对AZ91合金微观组织、力学性能、腐蚀性能的影响,考察钇在合金中所形成的稀土相组成和形貌。结果表明,钇在AZ91合金中生成Al4MgY相,可起非均质形核作用,减少二次枝晶间距,细化枝晶组织。加入钇后,合金腐蚀性能得到明显改善,由严重的全面腐蚀向只有表面部分位置有轻微点蚀的均匀腐蚀转变。当钇加入量为1.25%时,合金的室温和高温力学性能最好,分别为264.8MPa和164.8MPa。     

新型复合熔剂对AZ91镁合金组织和力学性能的影响

利用金相显微镜、X-射线衍射仪、SEM、EDAX、数字显微硬度计和电子万能试验机,对采用传统覆盖剂和自制覆盖剂制备的AZ91镁合金的显微组织和力学性能进行了分析。结果表明,自制覆盖剂制备的AZ91镁合金,Mg17Al12相得到改善,晶内出现Al4C3形核质点,晶粒得到显著细化,抗拉强度、屈服强度和延伸率都得到较大的提高,综合性能是实验合金中最高的,且拉伸断口形貌呈现河流花样,韧窝较深,这与合金的组织更细小有关。     

Effect of Yttrium Addition on Microstructures and Room Temperature Tensile Properties of Ti-47Al Alloy

The microstructures and room temperature tensile properties of a series of Ti-47Al-xY （x = 0%, 0.1%, 0.3%, 0.5%, 0.7% and 1.0%（atom fraction）） were investigated systemically. Results show that both the grain size and lamellar spacing decrease remarkably with the increase of Y content. When the content of Y is greater than 0.1%, most of the Y elements accumulate along the grain boundaries and some fine particles are uniformly dispersed within the grains in the form of YAl2 compound because of the low solubility and segregation of Y in TiAl alloys. Grain-boundary seg- regation of Y element is more prominent with the increase of Y addition. Good tensile properties are obtained when Y addition ranges from 0.3 % to 0.5 %. The refinement of grain and lamellar structures and dispersion of YAl2 within the grains contribute to the improvement of tensile properties. On the other hand, for high Y-added alloys （over 0.5% Y）, tensile properties are obviously deteriorated due to brittle cleavage fracture of the coarse YAl2 network.     

钇对铜和铜硅合金组织与性能的影响

用扫描电镜、能谱仪、Ｘ射线衍射、硬度测量等方法，研究了铜钇和铜硅钇合金的组织与性能。实验表明，钇的加入对铜和铜硅合金的组织有明显的变质作用，并提高了合金的硬度。