轧制温度对Al−4.5Cu−1.5Mg−0.5Zr合金显微组织及性能影响

目的 优化加工工艺,改善合金的组织,提高合金的力学性能。方法 采用金相(OM)观察、拉伸试验和X射线衍射,分析在大应变轧制下冷轧结合T6态处理后板材的成形性能,引入Williamson-Hall模型和Taylor函数,分析合金内部位错密度的变化规律及其对力学性能的影响。结果 随着前期轧制温度从350 ℃升高到400 ℃,合金晶粒得到明显细化,再结晶充分,晶粒尺寸细小,晶界处第二相粗大;冷轧后晶粒破碎严重,晶粒的碎化方向与轧制方向垂直;在350 ℃时,合金内部的位错密度为1.62×10¹⁵ m^?2,位错密度对强度的贡献值为219.5 MPa,其抗拉强度最大为602 MPa、屈服强度为512 MPa、伸长率为12.6%。结论 Al?4.5Cu?1.5Mg?0.5Zr合金的晶粒组织明显细化,其力学性能得到提升。     

喷射沉积连续挤压Al-20Si合金的微观组织及磨损性能

喷射沉积连续挤压技术是由喷射成型和连续挤压复合而成的新技术。本试验采用自制的喷射沉积连续挤压设备,在多种过热度条件下完成了Al-20Si合金的喷射沉积连续挤压试验,获得了8mm的铝合金杆件制品,分别对其显微组织和摩擦磨损性能进行研究。结果表明:喷射沉积连续挤压工艺可有效抑制初生硅的形核和生长,制备的铝硅合金中初生硅的尺寸约3~8μm,较铸态组织有明显细化,使得其耐磨性能提升1~2倍;随过热度的增加,喷射沉积连续挤压铝硅合金中初生硅的尺寸不断减小且分布更加弥散,使得合金的耐磨性更加优良。     

Co对Al-5％Fe合金铸态组织的影响

研究了Co对Al-5％Fe(质量分数，下同)合金中Al3Fe相形貌的改善作用。合金中加入Co后可以在很大程度上改善Al3Fe相的形貌：未加Co的Al-5％Fe合金中的Al3Fe相大多为粗大的针状和片状；Co的加入量为O．2％时，Al3Fe相的形貌为小花朵状和细小条状；Co的加入量在0．2％～1．0％时，细化效果较好，但尤以0．2％为最好，Co的加入量超过1．0％后，Al3Fe相开始略微粗化。在对Co元素的面扫描时发现其大多固溶在Al3Fe相内。X衍射分析发现，Co的量为0．2％和1．0％时合金中只存在Al和Al3Fe相，并未发现其它相。     

Co对Al-5%Fe合金铸态组织的影响

研究了Co对Al-5?(质量分数,下同)合金中Al3Fe相形貌的改善作用.合金中加入Co后可以在很大程度上改善Al3Fe相的形貌:未加Co的Al-5?合金中的Al3Fe相大多为粗大的针状和片状;Co的加入量为0.2%时,Al3Fe相的形貌为小花朵状和细小条状;Co的加入量在0.2%～1.0%时, 细化效果较好,但尤以0.2%为最好,Co的加入量超过1.0%后,Al3Fe相开始略微粗化.在对Co元素的面扫描时发现其大多固溶在Al3Fe相内.X衍射分析发现,Co的量为0.2%和1.0%时合金中只存在Al和Al3Fe相,并未发现其它相.     

Al-Ti-C-B晶种合金对Al-12Si-4Cu-2Ni-1Mg合金组织及力学性能的影响

目的 以近共晶Al-12Si-4Cu-2Ni-1Mg合金为研究对象,对加入了Al-Ti-C-B晶种合金的Al-12Si-4Cu- 2Ni-1Mg合金的微观组织和力学性能进行分析。方法 利用金相显微镜、扫描电镜、数显布氏硬度计和万能拉伸试验机等研究Al-Ti-C-B晶种合金对该合金显微组织和力学性能的影响。利用Al-Ti-C-B晶种合金中的陶瓷颗粒对Al-12Si-4Cu-2Ni-1Mg合金进行强化,同时晶种合金中的粒子作为Al-Si多元合金中α-Al的有效形核衬底,可细化α-Al晶粒,并改善Al-Si多元合金中化合物的分布。结果 加入质量分数为0.5%的Al-Ti-C-B晶种合金后,Al-12Si-4Cu-2Ni-1Mg合金中的α-Al得到细化,合金中的Si相和耐热相粒子分布更加均匀,同时力学性能明显提高,高温抗拉强度和室温抗拉强度分别提高了约12.1%和5.3%。结论 适量添加Al-Ti-C-B晶种合金可有效改善Al-12Si-4Cu-2Ni-1Mg合金中耐热相的分布,使耐热相分布更为均匀,可进一步提高合金的力学性能。     

Microstructure of Rapidly Solidified Al-3.8Li-0.8Mg-0.4Cu-0.13Zr Alloy by Spray Deposition Processing

Microstructure of rapidly solidified Al-3.8Li-0.8Mg-0.4Cu-0.13Zr alloy prepared by spray deposition has been investigated. The grains are 5~ 20μm in size, and the microstructure exhibits the rapid solidification merits. Shrinkage porosities have been avoided, and the formation of prior particle boundary (PPB) has been prevented to a large extent. But there still exist some micropores with various shapes. The relative density of the as-deposited material is 94% on average.The main precipitates in the tested alloy are δ(AlLi), S(Al2CuMg) and δ'(Al3Li) phases.     

Effect of processing on microstructure and wear characteristics of an Al-4·5Cu-10Pb alloy

An Al-4·5Cu-10Pb alloy was processed by spray forming as well as impeller mixing followed by chill casting methods. The microstructure, mechanical properties and dry sliding wear characteristics of the alloy were evaluated. The spray formed alloy showed an equiaxed grain morphology with a uniform dispersion of lead particles in the matrix phase. In contrast a cellular-dendritic morphology of the primary phase was the characteristic feature of the alloy processed by impeller mixing and chill casting method. The spray formed alloy indicated its superior mechanical properties and low wear rate particularly at higher applied load and sliding velocity. The possible reason for this behaviour is discussed in the light of microstructure of the alloy and the nature of the worn out surfaces of the wear test specimens.     

含钪Al-Cu-Li-Zr合金的抗晶间腐蚀和剥落腐蚀性能

通过晶间腐蚀、剥落腐蚀和极化曲线试验,结合扫描电镜和透射电镜等分析手段,研究了含钪Al-Cu-Li-Zr合金在不同时效状态下的晶间腐蚀和剥落腐蚀行为.结果表明,合金在自然时效状态下具有较好的抗晶间腐蚀和剥落腐蚀能力,但随着时效时间的延长,其晶间腐蚀与剥落腐蚀倾向逐渐增加;在4.0 mol/L NaCl 0.1 mol/L HNO3 0.4 mol/L KNO3(EXCO)溶液中进行的极化曲线测试也表现出相同的趋势.透射电镜观察表明,自然时效态合金未析出Г1相,欠时效态合金中有少量细小短棒状Г1相析出,随着时效时间的延长,Г1相逐渐粗化,过时效时合金中出现较宽的无沉淀带(PFZ).由于合金中Г1相和PFZ的开路电位都比铝基体低,在腐蚀过程中作为阳极相优先溶解,从而引起合金晶间腐蚀和剥落腐蚀.     

Al-5Ti-0.25C细化剂对2024铝合金组织及力学性能的影响

研究了Al-5Ti-0.25C细化剂对2024铝合金铸态显微组织及力学性能的影响。试验结果表明:未添加细化剂时,2024铝合金显微组织呈粗大的枝晶状,平均尺寸约为150μm;添加Al-5Ti-0.25C后,晶粒为细小的等轴晶。本试验条件下,最佳的细化剂添加量为0.3%,此时,2024铝合金的平均晶粒尺寸为56μm,其力学性能得到显著提高,抗拉强度和延伸率分别为382 MPa、2.60%,与未细化试样相比增幅分别为12.4%、69.9%。     

淬火温度对Ti-3Al-4.5V-5Mo钛合金形变诱发马氏体的影响

通过测试不同淬火温度下的拉伸应力应变曲线、750～790℃淬火拉伸断裂后均匀变形区域的X射线衍射谱研究了淬火温度对Ti-3Al-4.5V-5Mo钛合金形变诱发马氏体的影响.结果表明:该合金在750～790℃淬火后拉伸变形机制为亚稳定β相变形诱发马氏体转变,790℃淬火合金在6.5%的变形量下亚稳定β相基本完全转变为α″马氏体.790℃淬火后拉伸形成应力诱发马氏体,β立方→α″σ;750℃淬火后拉伸形成应变诱发马氏体,β立方→β正方→α″ε.形变诱发α″相在拉伸变形时发生晶格重新取向:[010] α″方向平行于拉伸轴线,[100]α″方向垂直于拉伸轴线.     

Al-4.72Cu-0.45Mg-0.54Ag-0.17Zr合金高温持久后的剩余室温拉伸性能及组织分析

研究了Al-Cu-Mg-Ag合金在165℃时效组织与性能的变化,并分别采用欠时效和峰值时效的试样进行200℃及外加应力为200MPa高温持久实验.结果表明,欠时效态的试样在高温持久下,随时间延长,其剩余强度先上升后下降,强度峰值出现在持久20h.延伸率变化与强度变化基本相似.持久100h后,合金力学性能相对欠时效态无明显下降,显示出优良的热稳定性.合金欠时效的高温持久后的性能优于峰时效态.     

Microstructures and Mechanical Properties of TiCp／A1-4.5Cu-0.8Mg Composites by Direct Reaction Synthesis

Direct reaction synthesis (DRS), based on the principle of self-propagating high-temperature synthesis (SHS), is a new method for preparing particulate metal matrix composites. TiCp/Al-4.5Cu-0.8Mg composites were fabricated by DRS. Particulate composites were fabricated with Ti carbide (TiC) particles, generally less than 1.0μm. The reacted, thermal extruded samples exhibit a homogeneous distribution of fine TiC particles in Al-4.5Cu-0.8Mg matrix.Mechanical property evaluation of the composites has revealed a very high tensile strength relative to the matrixalloy. Fractographic analysis indicates ductile failure.     

Microstructures and Mechanical Properties of TiC_P/Al-4.5Cu-0.8Mg Composites by Direct Reaction Synthesis

Direct reaction synthesis (DRS), based on the principle of self-propagating high-temperature synthesis (SHS), is anew method for preparing particulate metal matrix composites. TiCp/Al-4.5Cu-0.8Mg composites were fabricatedby DRS. Particulate composites were fabricated with Ti carbide (TiC) particles, generally less than 1.0 μm. Thereacted, thermal extruded samples exhibit a homogeneous distribution of fine TiC particles in Al-4.5Cu-0.8Mg matrix.Mechanical property evaluation of the composites has revealed a very high tensile strength relative to the matrixalloy.Fractographic analysis indicates ductile failure.     

新型Mg-8Li-5Al-5Ca合金的微观组织、力学及耐腐蚀性能

设计了新型高钙铝比Mg-8Li-5Al-5Ca合金,通过常温拉伸、失重法、pH测定和电化学测试等方法研究了合金的常温力学性能和耐腐蚀性能。采用扫描电镜(SEM)和X射线衍射(XRD)分析了基体和腐蚀产物相结构、合金显微组织以及腐蚀形貌。研究结果表明,这种镁锂合金形成Al2Ca相包围双基体(α-Mg+β-Li)的结构,挤压后基体组织和第二相粒子均明显细化。Mg-8Li-5Al-5Ca合金的耐腐蚀性能优于一般镁锂合金,且随着挤压比的增大进一步提升。该合金的力学性能协调了镁锂合金的优良塑性和高钙铝比镁合金的高强度,拥有较高的抗拉强度(222 MPa)和延伸率(8.3%)。     

Li对Al-3.5Cu-1.5Mg合金组织与性能的影响

采用光学显微镜(OM)、透射电镜(TEM)、扫描电镜(SEM)、维氏硬度计和力学性能测试等方法研究了Li元素对Al-3.5Cu-1.5Mg合金微观结构及性能的影响。结果表明:在Cu/Mg原子比约为1的Al-3.5Cu-1.5Mg实验合金中,加入1%(质量分数)的Li元素,主要时效析出相由S′(Al2CuMg)转变为S′(Al2CuMg)+δ′(Al3Li),晶界无沉淀析出带(PFZ)窄化;弹性模量提高了8GPa,抗拉强度提高了21MPa,伸长率由20.3%降至15.8%,由韧性断口转变为韧/脆混合型断口。     

真空熔结镍基合金涂层的组织结构及其高温磨损特性

研究了一种真空熔结镍基合金涂层的组织结构及其于摩擦滑动磨损特性。结果表明,镍基合金涂层中的析出相主要有硼化物,碳化物起强化作用,硅化物改善涂层熔结过程中的工艺性能。涂层磨损的主要方式是微犁削,因镍基合金涂层具有较高的高温硬度,高温下具有良好的抗菌性能,磨损过程中在磨损表面覆盖的氧化物层对涂层起到保护和减磨作用。     

原位自生TiB2/Al-4.5Cu复合材料微观组织和力学性能

采用混合盐反应法制备TiB2含量分别为0%,2%,5%,8%(质量分数,下同)的TiB2/Al-4.5Cu复合材料,T6热处理后,采用XRD,ICP,OM,SEM,EDS等测试手段和室温拉伸实验进行微观组织观察和力学性能测试。XRD和ICP测试证实,合金体系中仅含α-Al,Al2Cu及TiB2,无Al3Ti,Al2B等反应中间产物。OM和SEM发现,基体材料中α-Al平均晶粒尺寸为167.5μm,而在2%,5%,8%的TiB2/Al-4.5Cu中,其平均晶粒尺寸依次为110.4,87.2,75.2μm,晶粒细化效果显著。TEM观察发现,TiB2颗粒主要分布在晶界处,呈四方和六方结构。室温拉伸实验表明,随着TiB2含量的增加,强度、显微硬度值均呈增加趋势,但伸长率不断下降。当加入8%TiB2时,屈服强度、抗拉强度、弹性模量和显微硬度分别达到356 MPa,416 MPa,92.5GPa和96.5HV,但其伸长率从10.3%降低到4.3%。载荷传递强化、细晶强化、位错增殖强化是TiB2/Al-4.5Cu复合材料力学性能得以大幅提升的影响因素,尤其是在位错增殖强化作用下,TiB2颗粒周边致密分布的位错胞、位错环对强度的提升起到了决定性作用。     

Properties and Structural Changes of Al-3Cu-2Li Alloy after Thermal Treatment

A quantitative evaluation of microstructure and some mechanical properties of Al-3Cu-2Li (wt.%) alloy submitted to solution annealing at 503°C with succeeded age-hardening at three selected temperatures 163°C, 180°C and 190°C for 17 hours were investigated. With increasing the temperature of artificial ageing increases the strength of the alloy and reaches the maximum at 190°C, what is connected with decreasing of the deformation characteristics. Besides precipitates of Al₂Cu and Al₂CuLi the Cu₃Al particles were found.     

Thermal conductivity of Cu-4.5 Ti alloy

The thermal conductivity (TC) of peak aged Cu-4.5 wt% Ti alloy was measured at different temperatures and studied its variation with temperature. It was found that TC increased with increasing temperature. Phonon and electronic components of thermal conductivity were computed from the results. The alloy exhibits an electronic thermal conductivity of 46.45 W/m.K at room temperature. The phonon thermal conductivity decreased with increasing temperature from 17.6 at 0 K to 1.75 W/m.K at 298 K, which agrees with literature that the phonon component of thermal conductivity is insignificant at room temperature.     

Y对Zn-25Al-5Mg-2.5Si合金铸态组织及力学性能的影响

以Zn-25Al-5Mg-2.5Si合金为基体材料,通过常规铸造方法制备了加入不同含量稀土Y的锌铝合金.采用扫描电镜、拉伸试验机、硬度计等分析研究了稀土Y对合金显微组织和力学性能的影响.实验结果表明,添加稀土Y后,在锌铝合金中,其与Al、Zn等元素形成硬度高、热硬性好的复杂成分化合物,分散于晶界和枝晶中,细化了组织,有效地阻碍了高温时基体的变形和晶界移动.随着Y含量的增加,在室温、100℃和180℃时合金的抗拉强度基本呈先升后降的趋势.当Y含量为0.4%(质量分数)时合金的综合性能最好,高温强度和硬度显著提高.180℃时合金的抗拉强度比不加Y时提高了26.4%,硬度提高了47.8%.