Effect of Cd and Sn Addition on the Microstructure and Mechanical Properties of Al-Si-Cu-Mg Cast Alloy

The present work has investigated the effect of trace elements Cd and Sn on the microstructure and mechanical properties of Al-Si-Cu-Mg cast alloy. With the increase of Cd addition the strength of alloy rises at first and then drops. The optimal amount of Cd and Sn addition for AI-Si-Cu-Mg alloy is about 0.27% and 0.1% respectively. Due to the formation of some coarse Cd-rich phases and pure Cd particles the mechanical properties of alloy decrease when Cd amount exceeds 0.27%. When more than 0.1% Sn added, some Sn atoms form low-melting eutectic compound at grain boundary, and then cause over-burning in alloy when solution treated, which may deteriorate properties of alloy, especially ductility of alloy.On the other hand, the addition of Cd and Sn remarkably increases the peak hardness and reduces the time to reach aging peak in Al-Si-Cu-Mg alloy. The action of Cd/Sn in quaternary Al-Si-Cu-Mg alloy is effectively the same as that occur in binary Al-Cu alloy that the enhanced hardening associated with Cd/Sn addition is due to the promotion of the θ‘phase.     

Cd对铸造Al-Si-Cu-Mg合金时效过程的影响

合金元素Cd的添加促进了铸造Al-Si-Cu-Mg合金的时效过程，提高了合金的峰时效硬度，加快了合金的硬化速度．当加入0．27％Cd时，合金的强度提高了20％；但加入量继续增大，强度反而降低．SEM，DSC和TEM分析显示，Cd加快了亚稳相的析出，较早地形成了细小而密集的亚稳相；同时，较大的富Cd相、少量稳定相和过剩硅相质点的均匀析出，对合金起到了第二相强化的作用．在这两类析出相的共同作用下，合金获得了高的峰时效强度．但当合金中Cd的含量超过0．27％时，会形成一些富Cd的多元相和纯Cd质点，这些相的出现导致了合金机械性能的下降．     

微量元素对ZTC4显微组织与力学性能影响

采用熔铸工艺法制备了含硼量为0.2%~0.5%、碳为0.5%~3.0%、钇为0.1%~0.15%的ZTC4/B/C/Y钛基复合材料,分析并测试了合金的铸态组织和力学性能。研究结果表明:钛硼相提高TC4合金铸棒弹性模量,硼元素添加量为0.5%时,合金弹性模量提高30%;C元素大大提高ZTC4合金铸棒的强度,添加0.5%C元素,其抗拉强度达到1 300 MPa,提高了25%;Y元素的添加,在ZTC4合金铸棒的塑性不明显降低的基础上,改善合金的强度,具有较好的强塑性匹配。     

Effect of Rare Earth Sc Addition on Microstructure and Mechanical Properties of an Al-Cu-Mg-Ag Alloy

Al-5.3Cu-0.8Mg-0.6Ag alloys containing 0, 0.1, 0.3 and 0.5 (mass. %) Sc were prepared by ingot metallurgy and thermomechanical treatment. The effect of Sc addition on the precipitation and microstructure of the alloys has been investigated using mechanical testing, optical microscope, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It has been shown that trace Sc element refines the grains of the casting alloys and the average grain size decreases from 85 μm to 30 μm. Increasi...     

Effects of Cd and Sn on double-peak age-hardening behaviors of Al-Si-Cu-Mg cast alloys

The effects of trace elements Cd and Sn on precipitation process of Al-Si-Cu-Mg cast alloys were investigated in the present research.It is shown that the addition of Cd and Sn not only increases remarkably the aging peak hardness and reduces the time to reach aging peak,but also eliminates the double-aging-peak phenomenon which appears in Al-Si-Cu-Mg alloys.In Al-Si-Cu-Mg alloys the first aging peak corresponds to GP zones(especially GPⅡ) ,and the second one is caused by metastable phases.The obvious time interval of transition from GPⅡ to metastable phases associates with the double-aging-peak phenomenon.The results of DSC and TEM show that Cd/Sn elements suppress the formation of GPⅠzone,stimulate the formation of θ",θ' and θ phases,and then shorten remarkably the temperature intervals of each exothermic peak.Because the transition interval between GPⅡzone and metastable phases is shortened by Cd/Sn in Al-Si-Cu-Mg cast alloys,θ' phase coexists with θ" phase in matrix of ageing peak condition,which causes effective hardening on the alloys,and at the same time,eliminates the double-aging-peak phenomenon.     

Effect of Friction Stir Processing on Microstructure and Mechanical Properties of Cast AZ31 Magnesium Alloy

对铸态AZ31镁合金进行单道次和双道次搅拌摩擦加工,对其微观组织和力学性能进行研究.结果表明:铸态AZ31镁合金搅拌摩擦加工后,共晶网状β-Mg17Al12相破碎并发生固溶,微观组织显著细化和均匀化.AZ31镁合金母材和单道次搅拌摩擦加工后的试样没有择优取向,而双道次搅拌摩擦加工后的试样存在择优取向,其(0002)基平面与试样表面平行.单道次和双道次搅拌摩擦加工后试样的抗拉强度分别提高了43和82MPa,延伸率提高了4.3％和11.9％.搅拌摩擦加工后试样的拉伸断口表现为韧性断裂特征.     

微量元素Cr对ZL101合金微观组织和力学性能的影响

本文采用真空电磁感应熔炼炉制备了ZL101-xCr(x=0、0.1、0.2、0.3、0.5、0.8wt.%)铝合金。利用OM、XRD、SEM、EDS及TEM等测试方法,表征了不同Cr含量实验合金微观组织,并测试其力学性能。结果表明：实验合金主要物相包括初晶α-Al、(α-Al+Si)共晶、Al₁₃Cr₄Si₄、α-Al₁₂(Cr, Fe)₃Si₂、富Fe相(β-Al₅FeSi和π-AlSiMgFe)。添加微量元素Cr后的实验合金组织均得到细化,随着Cr含量的增加,α-Al树枝晶趋于等轴晶转变,共晶组织区域变窄,富Fe相和共晶Si尺寸变小,在合金共晶组织中形成了Al₁₃Cr₄Si₄、α-Al₁₂(Cr, Fe)₃Si₂相。添加Cr元素能够提高合金的过冷度,这对细化合金组织具有积极作用。当Cr含量为0.3%时,铸造合金组织细化变质效果及其力学性能最好,抗拉强度、伸长率分别为182.88Mpa、3.38%。     

铸造新型高性能合金的组织与性能的研究

设计了用于“氧化－还原”复合介质的铸造新型高性能合金的化学成分,采用金相显微镜、X射线衍射和电子探针等手段观察与分析了合金的金相组织,并研究了新型合金的均匀腐蚀、晶间腐蚀与电化学腐蚀行为。试验结果表明,低的合碳量和适量的Ni、Cr、Mo、W的复合作用,使该合金对还原性和氧化性介质均具有良好的耐蚀性和较高的抗点蚀性能、此外,该合金还具有良好的综合机械性能与满意的铸造性能。     

Mg对Al-Cu-Mn-Ag合金的组织与力学性能的影响

通过铸锭冶金及形变热处理,制备了不同Mg含量的Al-Cu-Mn-Ag合金。采用拉伸测试、差热分析（DSC）、扫描电镜（SEM）及透射电镜（TEM）研究了Mg含量对合金显微组织与力学性能的影响。结果显示,添加微量Mg,改变了基体合金的时效硬化过程与析出相种类。185℃峰时效时,Al-4.45Cu-0.49Mn-0.58Ag-0.82Mg合金的主要强化相由片状Ω相和少量θ＇相组成。增加Mg的含量,能降低Ω相的尺寸,提高其拉伸性能。     

Effect of Cd Addition on Microstructure and Properties of Mg-Cd Binary Magnesium Alloy

研究了Cd对Mg-Cd二元合金组织和性能的影响。通过XRD、SEM和EDS对加入Cd镁合金金相进行了检测。研究结果表明：在纯镁中加入微量的Cd能明显的细化组织,并且加入从0%到0.7% (质量分数)的Cd后,在Mg-Cd合金中没有新相产生,Cd均匀、弥散的固溶在镁基体中,使合金的冲击韧度、布氏硬度分别提高了52.9%,11.9%,且随着Cd加入量的增加,Mg-Cd二元合金的力学性能在逐渐的增加     

添加钇对Pt-5Cu合金组织结构和性能的影响

采用真空电弧熔炼方法制备了Pt-5Cu、Pt-4.9Cu-0.10Y和Pt-0.48Cu-0.20Y合金。利用X射线衍射仪(XRD)、金相显微镜、显微硬度仪及分光光度计等研究了Pt-Cu及Pt-Cu-Y合金的物相组成、显微组织结构、力学性能及反射率。结果表明,钇对Pt-Cu合金的相结构无明显影响,当钇的添加量为0.20%时,Pt-Cu合金的晶粒尺寸显著细化,晶粒的平均尺寸由约150μm降至约80μm;细晶强化使Pt-Cu合金的维氏硬度显著增加到165;在可见光波段内,Pt-Cu及Pt-Cu-Y合金的反射率无明显差别。     

合金元素对ZL107组织与力学性能的影响

为提高ZL107合金的力学性能，研究了Ti、B、Cd、Mg、Zn、Ag等合金元素对ZL107合金显微组织和力学性能的影响。结果表明，Ti、B使合金晶粒细化，改善显微组织；Cd、Mg、Zn可以提高合金的抗拉强度和硬度；而Ag的加入可以显著提高合金的伸长率。通过加入以上几种合金元素并配以合适的热处理工艺，可以进一步提高ZL107的综合力学性能。采用51012固溶处理和150℃时效处理时可以得到较好的强度和塑性配合。     

Zn添加对Mg-8Al-2Sn镁合金组织和性能的影响

本文以Mg-8Al-2Sn变形镁合金为研究背景,通过在Mg-8Al-2Sn合金中添加0-2 wt.%含量的Zn元素,研究了Zn添加对Mg-8Al-2Sn挤压镁合金显微组织和性能的影响。研究结果表明,铸态Mg-8Al-2Sn-xZn合金的相组成主要是α-Mg相、Mg₁₇Al₁₂相和Mg₂Sn相。在添加Zn元素以后,合金中的共晶化合物的形态发生变化,由共晶组织变为离异共晶组织。挤压过后,晶粒组织尺寸更均匀。Zn元素的加入,会促进合金中第二相在挤压过程中的动态析出以及第二相尺寸的粗化。合金在时效中产生的析出相的数量也随着Zn含量的增多而增加。随着Zn含量的增加,挤压态和时效态合金的屈服强度和抗拉强度都随之增加。当Zn含量达到2 wt.%时,合金力学性能最好,其时效态的抗拉强度,屈服强度和延伸率分别是385 MPa, 291 MPa和6.44%。     

Sn对AM60镁合金显微组织及力学性能的影响

分析了Sn对AM60镁合金显微组织及力学性能的影响。结果表明：AM60镁合金中加入Sn形成的Mg：Sn颗粒相能够细化合金晶粒,晶间组织β相由连续网状转变为不连续,提高了合金的力学性能。当Sn质量分数为1．2％时,合金的力学性能最佳,合金拉伸断裂方式由解理断裂变为准解理断裂;随着Sn元素含量的继续增加,其力学性能又逐渐降低。     

Sn含量对二元Mg-Bi合金显微组织和力学性能的影响

采用OM、SEM、XRD、EDS、维氏硬度计和电子拉伸试验机研究了Sn对Mg-3.3Bi合金显微组织和力学性能的影响。结果表明:加入Sn后,合金晶粒尺寸随着Sn含量的增加先减小后增大,在添加4%Sn时最小;Sn元素能在显微组织中形成规则球状的Mg2Sn相,Mg2Sn相具有高硬度、高熔点以及热稳定性好的优点,对Mg-3.3Bi-Sn合金具有很好的强化效果;Sn元素在0~6%变化时,合金的抗拉强度、伸长率和硬度都呈现先升高后降低的趋势,当Sn含量为4%时合金的力学性能出现最佳配合。     

微量Zr对铸造TiAl合金高温力学性能的影响

在Ti-47.5Al-2.5V-1.0Cr合金中添加0.2at.％Zr以研究微量Zr对铸造形成的定向层片组织高温力学性能的作用.结果表明,添加0.2at.％Zr显著提高了该合金的持久寿命,但未对其高温拉伸强度产生明显影响.根据两种合金持久试验前后组织对比观察的结果提出,添加微量Zr主要是通过增加定向层片组织的热稳定性而使其持久性能得以改善;另外,微量Zr减少了热等静压过程中等轴晶粒的析出,也有助于延长合金的持久寿命.     

Effects of Solution Treatment on the Microstructure and Mechanical Properties of Al-16.9Si-4.5Cu-0.15Mg Alloy

In this paper, the microstructure and mechanical properties of Al-Si-Cu-Mg casting alloy under different solution conditions were investigated by optical metallographic and mechanical property test. The results show that the cast alloys were composed of α-Al, primary Si, eutectic Si, Al2Cu and Al7Cu2Fe phases. Three changes took place during solution treatment: Firstly, with the increase of solution temperature and the solution holding time extension, more and more Al2Cu phase was dissolved into the matrix; Secondly, with the increase of solution temperature and the solution holding time extension, morphology of eutectic Si, Al7Cu2Fe and other insoluble phases changed into more round; Thirdly, at the fixed solution temperature, if the solution time extended too long, it would cause grains, eutectic Si and other insoluble phases aggregated and coarsened. About mechanical properties, when the solution time was fixed, the hardness, tensile strength and the yield strength of the Al-Si-Cu-Mg alloy treated by T6 enhanced while the solution temperature increasing, and when the solution temperature was fixed, the ultimate tensile strength and the elongation of the Al-Si-Cu-Mg alloy treated by T6 increased at first and then decreased while the solution time increasing, but the hardness of the alloys affected less by the solution time.     

Effect of Trace Boron Addition on Microstructure and Properties of as-Cast Ti-6Al-4V Alloy

通过添加0.1wt%B对铸态Ti-6Al-4V合金组织和性能影响研究表明:微量B添加在合金中形成Ti B相,Ti B相位于原始β晶界处。微量的B添加使得原始β晶粒和α集束都得到了明显的细化,获得的铸态组织更加均匀。微量的B添加同时提高了铸态合金的强度和塑性,并改变了合金的拉伸断裂机制。由微空洞在α集束交界处聚集、长大及裂纹形成扩展改变为Ti B相与基体合金的变形不协调造成微裂纹的形成和扩展。     

感应淬火对合金铸铁组织与油摩擦性能的影响

目的 优化感应淬火工艺,为提高合金铸铁表面硬度及耐磨性能提供理论依据。方法 通过热力学计算和同步热分析法测试分析了合金铸铁相变规律,并对该材料在6 kW和8 kW功率下进行了2~8 s高频表面淬火。采用扫描电镜(SEM)、洛氏硬度计、摩擦磨损试验机,研究了不同感应淬火工艺对合金铸铁显微组织、硬度和摩擦磨损性能的影响。结果 合金铸铁经感应淬火后,组织为珠光体+马氏体+石墨+磷共晶,随加热时间延长,马氏体含量增多,珠光体与磷共晶逐渐减少,直至6 kW/8 s、8 kW/6 s时消失,但是继续延长时间会产生裂纹。硬化区硬度随加热时间增长而提高,峰值为50HRC,二者的关系可用Logistic曲线描述。硬度升高会提升耐磨性,超过一定硬度后,摩擦系数在0.11波动。不同形式的裂纹可以造成磨痕宽度具有不同的变化规律。结论 感应淬火可有效提升合金铸铁的表面硬度及油摩擦性能。     

钐含量对镁合金微观组织和力学性能的影响

借助光学显微镜、扫描电镜和电子万能试验机研究AM90合金中加入钐(Sm)后的显微组织和力学性能,并分析Sm对合金显微组织和力学性能的影响.结果表明:AM90-xSm合金是由α-Mg、β-Mg17Al12和Al2Sm金属间化合物组成.随着Sm含量的增加,β-Mg17Al12相的尺寸减小,AM90-xSm合金的晶粒得到细化.当Sm含量为2.0％时,屈服强度和极限抗拉强度分别达到最大值147MPa和168MPa.当Sm含量为1.0％时伸长率达到最大值,进一步增加Sm的含量时合金的伸长率有所降低.