Cu含量以及Cu/Mg比对Al-Si-Cu-Mg合金组织和力学性能的影响

研究了Cu含量和Cu/Mg比对Al-Si-Cu-Mg合金组织和力学性能的影响。结果表明Al-Si-Cu-Mg合金凝固组织是否形成Mg_(2)Si、Q-Al_(5)Cu_(2)Mg_(8)Si_(6)以及θ-Al_(2)Cu取决于Cu含量以及Cu/Mg比。当Cu/Mg比相对低时形成Mg_(2)Si中间相,而Cu/Mg比高时则倾向于生成Q-Al_(5)Cu_(2)Mg_(8)Si_(6)和θ-Al_(2)Cu相。当Cu/Mg比相同时,高Cu含量和高Mg含量都会促进Q相θ相的形成。通过观察T6热处理后的组织发现Cu含量以及Cu/Mg比控制了初生相的溶解以及析出相的形成,从而影响合金的强度与韧性。通过控制Cu含量及Cu/Mg比使Al-9Si-2Cu-0.5Mg合金中析出较少数量的初生相,再通过热处理析出大量的Q′强化相,使合金具有较高的强度和相对适中的伸长率。

Effect of minor Zr and Sc on microstructures and mechanical properties of Al-Mg-Si-Cu-Cr-V alloys

The effects of minor contents of Zr and Sc on the microstructures and mechanical properties of Al-Mg-Si-Cu-Cr-V alloy were studied. The results show that the effects of minor Zr and Sc on the as-cast grain refinement in the ingots, the improvement in the strength of the as-extruded alloys and the restriction of high angle grain boundaries in the aged alloys can be sorted as Al3ScAl3 （Zr,Sc）Al3Zr. None of them could stop the nucleation of recrystallization, but Al3 （Zr,Sc） phase is a more effective inhibitor of dislocation movement compared to Al3 Sc in the aged alloys. Compared with the mechanical properties of the aged alloy added only 0.15% Sc, the joint addition of Zr and Sc to the alloy leads to a very slight decrease in strength with even no cost of ductility. Taking both the production cost and the little bad influence on mechanical properties into consideration, an optimal content of Zr and Sc in the Al-Mg-Si-Cu-Cr-V alloy to substitute 0.15% Sc is 0.13% Zr＋0.03% Sc.

Mn对Al-Mg-Si-Cu铝合金结晶相的影响

通过扫描电镜/能谱、X射线衍射以及金相分析,针对含0.3%Fe(质量分数)的Al Mg Si Cu铝合金,研究了Mn含量对其结晶相的影响。研究表明:合金在铸造过程中形成的结晶相为Al1.9CuMg4.1Si3.3,Al5(FeMn)Si,Al8(FeMn)2Si以及少量的Mg2Si;增大含Mn量,合金中AlFeMnSi型结晶相数量增多;对合金进行均匀化处理时,Al1.9CuMg4.1Si3.3相完全溶解,发生Al5(FeMn)Si向Al8(FeMn)2Si相的转变;对合金进行轧制及最终热处理后,结晶相碎化且沿轧向呈纤维状分布,但结晶相的类型不变。

Effect of Ni on microstructure and mechanical properties of Al−Mg−Si alloy for laser powder bed fusion

The microstructures and mechanical properties were systematically studied for the high-strength Al−5Mg_(2)Si−1.5Ni alloy fabricated by laser powder bed fusion(L-PBF).It is found that the introduction of Ni(1.5 wt.%)into an Al−5Mg_(2)Si alloy can significantly improve the L-PBF processibility and provide remarkable improvement in mechanical properties.The solidification range of just 85.5 K and the typical Al−Al3Ni eutectics could be obtained in the Ni-modified Al−5Mg_(2)Si samples with a high relative density of 99.8%at the volumetric energy density of 107.4 J/mm^(3).Additionally,the refined hierarchical microstructure was mainly characterized by heterogeneousα-Al matrix grains(14.6μm)that contain the interaction between dislocations and Al−Al3Ni eutectics as well as Mg_(2)Si particles.Through synergetic effects of grain refinement,dislocation strengthening and precipitation strengthening induced by Ni addition,the L-PBFed Al−5Mg_(2)Si−1.5Ni alloy achieved superior mechanical properties,which included the yield strength of(425±15)MPa,the ultimate tensile strength of(541±11)MPa and the elongation of(6.2±0.2)%.

Mn微合金化Al-Si-Cu-Mg合金显微组织及耐蚀性能研究

Al-Si-Cu-Mg系列合金具有优异的强韧性,但其中的含Cu强化相极大地影响了该系合金的耐蚀性能。因此,本文通过对不同Mn含量的Al-7Si-2Cu-0.6Mg合金进行显微组织观察和电化学分析,探究Mn元素的添加对T6热处理状态下合金微观结构和耐蚀性的影响。结果表明,Mn添加量的提高对合金显微硬度几乎没有影响,但在合金基体中可以观察到弥散相。随着Mn含量升高,合金的耐蚀性呈现先升高后降低的趋势。添加0.360%Mn(质量分数)合金具有最佳耐蚀性,腐蚀电流密度比基础合金减少了54%。腐蚀形貌观察结果表明,Mn的添加可以显著减弱合金的点蚀趋势。

Influence of thermomechanical processing on microstructure,texture evolution and mechanical properties of Al-Mg-Si-Cu alloy sheets

Influence of thermomechanical processing on the microstructure, texture evolution and mechanical properties of A1-Mg-Si-Cu alloy sheets was studied systematically. The quite weak mechanical properties anisotropy was obtained in the alloy sheet through thermomechanical processing optimizing. The highly elongated microstmcture is the main structure for the hot or cold-rolled alloy sheets. H {001 } （110） and E { 111 } （110） are the main texture components in the surface layer of hot-rolled sheet, while ]/-fibre is dominant in quarter and center layers. Compared with the hot-rolled sheet, the intensities offl-fibre components are higher after the first cold rolling, but H {001 }（110） component in the surface layer decreases greatly. Almost no deformation texatre can be observed after intermediate annealing. And fl-fibre becomes the main texture again after the final cold rolling. With the reduction of the thickness, the through-thickness texture gradients become much weaker. The through-thickness recrystallization texture in the solution treated sample only has cubeyD {001 }（310） component. The relationship among thermomechanical processing, microstructure, texture and mechanical orouerties was analyzed.

Effect of particle size distribution on the microstructure,texture,and mechanical properties of Al–Mg–Si–Cu alloy

The effect of particle size distribution on the microstructure,texture,and mechanical properties of Al–Mg–Si–Cu alloy was investigated on the basis of the mechanical properties,microstructure,and texture of the alloy.The results show that the particle size distribution influences the microstructure and the final mechanical properties but only slightly influences the recrystallization texture.After the pre-aging treatment and natural aging treatment(T4 P treatment),in contrast to the sheet with a uniform particle size distribution,the sheet with a bimodal particle size distribution of large constituent particles and small dispersoids exhibits higher strength and a somewhat lower plastic strain ratio(r) and strain hardening exponent(n).After solution treatment,the sheet with a bimodal particle size distribution of large constituent particles and small dispersoids possesses a finer and slightly elongated grain structure compared with the sheet with a uniform particle size distribution.Additionally,they possess almost identical weak recrystallization textures,and their textures are dominated by CubeND {001}<310> and P {011}<122> orientations.

Study of rare earth element effect on microstructures and mechanical properties of an Al-Cu-Mg-Si cast alloy

The improvements of microstructures and properties of a high strength aluminum cast alloy were studied. The effects of rare earth elements on the microstructures and mechanical properties of the high strength cast alloy Al-Cu-Mg-Si were investigated. The result shows that the addition of rare earth elements can change the microstructures in refining the grain size of the alloy and making the needle-like and laminar eutectic Si to a granular Si. With the increase of the rare earth, the tensile strength and elongation of the alloy increase first and then fall down. The mechanical properties of the alloy will reach the highest value when the content of rare earth elements is about 0.7%.

热处理工艺对Al-Si-Mg-Cu合金微观组织和力学性能的影响

采用扫描电镜(SEM)、透射电镜(TEM)和万能拉伸试验机等研究了固溶温度、固溶时间、时效温度以及时效时间等工艺参数对Al-Si-Mg-Cu合金微观组织与力学性能的影响。结果表明,固溶温度由500℃升高至545℃时,合金的共晶硅尺寸逐渐减小,545℃时共晶硅平均尺寸达到最小,超过550℃合金会发生部分过烧现象;固溶温度为545℃时,固溶时间由2 h增加至16 h,共晶硅尺寸随着固溶时间增加先减小后增大,固溶时间为12 h时,共晶硅的平均尺寸最小;时效处理后合金的硬度显著提升,时效温度由155℃升高至185℃时,峰值时效时间从8 h减少至4 h,在175℃时效时合金的峰值硬度最高;155℃时效时合金的组织中仅观察到β″相,在高于155℃峰值时效时组织中均观察到β″相与θ′相,实现了双析出相强化,175℃峰值时效时合金的抗拉强度可达365 MPa,但断后伸长率下降至2.1%。综合考虑合金的强度和韧性,合适的热处理工艺为545℃×12 h+165℃×8 h。

Influence of Si Contents on the Microstructure Evolution and Mechanical Properties of Al-Mg-Si-Cu-Zn Alloys

The influence of different Si contents on the microstructure evolution and mechanical properties of Al⁃Mg⁃Si⁃Cu⁃Zn alloys was systematically studied using tensile testing,OM,SEM,EDS,and EBSD.The results indicate that the grain size of as⁃cast alloys was gradually reduced with the increase of the Si content,which mainly resulted from the formation of many iron⁃rich phases and precipitates during the casting process.During homogenization treatment,the plate⁃likeβ⁃AlFeSi phases in the alloy with a higher Si content easily transformed to the sphericalα⁃Al(FeMn)Si phases,which is helpful for improving the formability of alloys.The microstructure evolution of the alloys was also greatly dependent on the content of Si that the number density and homogeneous distribution level of precipitates in the final cold rolled alloys both increased with the increase of the Si content,which further provided a positive effect on the formation of fine recrystallization grains during the subsequent solution treatment.As a result,the yield strength,ultimate tensile strength,and elongation of the pre⁃aged alloys in the direction of 45°with respect to the rolling direction were all increased with increasing Si content.

Cu含量对Al-1Mg-0.6Si-xCu合金板材韧性及弯曲性能的影响

采用室温拉伸、Kahn撕裂以及弯曲实验,结合数字图像分析法和扫描透射电镜等手段,探究了Cu含量对Al-1Mg-0.6Si-xCu合金板材韧性及弯曲性能的影响。结果表明:随着Cu含量的增加,合金的伸长率、均匀伸长率、均匀断裂能和单位面积裂纹形核功逐渐增加,合金的弯曲性能变好,均匀阶段韧性提升,而合金的失稳伸长率、失稳断裂能及单位面积裂纹扩展功下降,合金失稳阶段韧性变差。随着Cu含量的增加,Al-1Mg-0.6Si-xCu合金中强化相β″的密度增加,且在0.5-Cu合金中出现Q′相和L相,晶内析出相密度增加,使得合金在形变过程中消耗的能量增加;晶界析出相间距增加,从而提高合金的韧性及弯曲性能。

Mg、Si含量对Al-Cu-Mg-Ag-Si合金析出相的影响

研究了Mg、Si元素含量对Al-Cu-Mg-Ag-Si合金实际析出相种类及性能的影响。结果表明,Al-Cu-Mg-Ag-Si合金中高Mg含Si合金析出了大量S相和粗大的第二相;低Mg低Si合金中析出了常见的θ相和Ω相;低Mg含Si合金中出现了6系铝合金中常见的σ相和β″相等多种析出相,且具有非常细小弥散的θ相,为合金提供了良好的强化效果。Si和Mg的存在均极大地改变了合金的析出序列,无法通过增加Mg含量抵消Si的作用。Si的加入显著抑制了Ω相的析出,而大幅增加Mg含量则会促进S相的析出。

时效时间对Al-Mg-Si-Cu铝合金表面阳极氧化膜微观结构及光泽度的影响

采用硫酸阳极氧化对经过180℃下4 h、10 h、30 h时效处理的Al-Mg-Si-Cu合金表面进行阳极氧化处理,探究不同时效时间对Al-Mg-Si-Cu合金阳极氧化膜层微观结构及其光泽度的影响。研究结果表明:与基体材料相比,不同时效时间合金阳极氧化后的光泽度均出现明显降低,且光泽度随时效时间增加先变大后减小;随时效时间增加,合金晶界析出相分别呈现连续—离散—连续的分布状态,其在阳极氧化过程中优先氧化溶解,使阳极氧化膜呈现沿晶界分布的孔洞特征,连续分布的晶界析出相引起的孔洞更明显,同时造成孔洞及其周围区域粗糙度增加,这是不同时效时间合金阳极氧化后光泽度出现差异的主要原因;基体中粗大的AlFeMnSi相会出现阳极氧化膜层中微米级孔洞,从而降低阳极氧化样品的光泽度,但时效时间对其没有明显影响。

末道次冷轧变形量对Al-Mg-Si-Cu合金织构和力学性能的影响

通过X射线衍射、电子背散射衍射技术和拉伸测试等研究了末道次冷轧变形量对汽车车身板用Al-Mg-Si-Cu合金板材织构、晶粒形貌和力学性能的影响。结果表明:在成分和冷轧后固溶处理工艺相同的情况下,织构是决定Al-Mg-Si-Cu合金板材力学性能的主要因素。晶粒尺寸最大的33%试样反而获得了最高的抗拉强度和较低的屈强比。这是因为减小末道次冷轧变形量可以降低固溶及预时效处理状态下板材Cube和Cube+ND_(20)织构的含量,从而减少立方型织构对板材强度的损害。而末道次大变形量冷轧会促进再结晶时Copper、S和Brass织构向Cube和Cube+ND_(20)织构的转变,并抑制S织构转变成R织构,在实际生产中应当避免。

Relationship among solution heating rate,mechanical properties,microstructure and texture of Al−Mg−Si−Cu alloy

The relationship among heating rate, mechanical properties, microstructure and texture of Al-Mg-Si-Cu alloy during solution treatment was investigated through tensile test, scanning electron microscope, X-ray diffractometer and EBSD technology. The experimental results reveal that there is a non-monotonic relationship among solution heating rate, mechanical properties, microstructure and texture. As the solution heating rate increases, the strength variations are dependent on the tensile direction;work hardening exponent n decreases first, and then increases;plastic strain ratio r increases first, and then decreases, and finally increases. The final microstructure and texture are also affected by heating rate. As heating rate increases, the microstructure transforms from elongated grain structure to equiaxed grain structure, and the average grain size decreases first, and then increases, and decreases finally. Although the texture components including CubeND{001}<310> and P{011}<122> orientations almost have no change with the increase of heating rate, the texture intensity and volume fraction decrease first, and then increase, and finally decrease. Both microstructure and texture evolutions are weakly affected by heating rate. Improving heating rate is not always favorable for the development of fine equiaxed grain structure, weak texture and high average r value, which may be related to the recrystallization behavior.

Ce-La添加量对汽车用Al-Si-Cu-Mg-Ni合金组织与力学性能的影响

对Al-Si-Cu-Mg-Ni合金中添加了不同量的Ce-La复合稀土,通过显微组织观察、力学性能测试研究了不同Ce-La复合稀土添加量对铸态Al-Si-Cu-Mg-Ni合金组织与力学性能的影响。结果表明:未添加稀土的Al-Si-Cu-Mg-Ni合金中有大量块状的初生Si相和针状共晶Si相存在。随着Ce-La复合稀土添加量的增加,合金中的初生Si相直径和共晶Si相尺寸先减小后增加。Ce-La稀土添加量为0.4wt%时,合金中的初生Si相直径和共晶Si相尺寸最小。随着Ce-La复合稀土添加量的增加,Al-Si-Cu-Mg-Ni合金的抗拉强度和伸长率先升高后降低,Ce-La复合稀土添加量为0.4wt%时,合金的抗拉强度和伸长率均达到最大值,分别为296.5 MPa和2.9%。

Effect of thermal exposure on microstructure and mechanical properties of Al-Si-Cu-Ni-Mg alloy produced by different casting technologies

The effect of thermal exposure at 350 ℃ for 200 h on microstructure and mechanical properties was investigated for Al-Si-Cu-Ni-Mg alloy, which was produced by permanent mold casting(PMC) and high pressure die casting(HPDC). The SEM and IPP software were used to characterize the morphology of Si phase in the studied alloys. The results show that the thermal exposure provokes spheroidization and coarsening of eutectic Si particles. The ultimate tensile strength of the HPDC alloy after thermal exposure is higher than that of the PMC alloy at room temperature. However, the TEPMC and TEHPDC alloys have similar tensile strength around 67 MPa at 350 ℃. Due to the coarsening of eutectic Si, the TEPMC alloy exhibits better creep resistance than the TEHPDC alloy under studied creep conditions. Therefore, the alloys with small size of eutectic Si are not suitably used at 350 ℃.

Microstructure, Texture, and Hardness Evolutions of Al-Mg-Si-Cu Alloy during Annealing Treatment

Microstructure, texture and hardness evolutions of Al-Mg-Si-Cu alloy during annealing treatment were studied by microstructure, texture and hardness characterization in the present study. The experimental results show that microstructure, texture and hardness will change to some extent with the increase of annealing temperature. The microstructure transforms from the elongated bands to elongated grains first, and then the grains grow continuously. The texture transforms from the initial deformation texture b fiber to recrystallization texture mainly consisting of CubeND {001}<310> and P {011}<122> orientations first, and then the recrystallization texture may be enhanced continuously as a result of the grain growth. Hardness decreases slowly at first, and then decreases sharply and increases significantly finally. Besides, the particle distributions also have great changes. As the annealing temperature increases, they increase firstly as a result of precipitation, and then gradually disappear as a result of dissolution. Finally, the effect of annealing temperature on microstructure, texture and hardness evolutions is discussed.

Influence of Cu content on microstructure and mechanical properties of thixoformed Al-Si-Cu-Mg alloys

The effects of Cu content on the microstructure and mechanical properties of thixoformed Al-6Si-xCu-0.3Mg(x= 3,4,5and 6,mass fraction,%) alloys were studied.The samples were thixoformed at 50%liquid content and several of the samples were treated with the T6 heat treatment.The samples were then examined by optical microscopy(OM),scanning electron microscopy(SEM),energy dispersive X-ray(EDX) spectroscopy and X-ray diffraction(XRD) analysis,as well as hardness and tensile tests.The results show that the cooling slope casting and thixoforming process promote the formation of very fine and well distributed intermetallic compounds in the aluminium matrix and the mechanical properties of the alloys increase considerably compared with the permanent mould casting.The results also reveal that as the Cu content in the alloy increases,the hardness and tensile strength of the thixoformed alloys also increase.The ultimate tensile strength,yield strength and elongation to fracture of the thixoformed heat-treated Al-6Si-3Cu-0.3Mg alloy are 298 MPa,201 MPa and 4.5%,respectively,whereas the values of the thixoformed heat-treated alloy with high Cu content(6%) are 361 MPa,274 MPa and 1.1%,respectively.The fracture of the thixoformed Al-6Si-3Cu-0.3Mg alloy shows a dimple rupture,whereas in the alloy that contains the highest Cu content(6%),a cleavage fracture is observed.

Effects of strain rate on mechanical properties, microstructure and texture of Al-Mg-Si-Cu alloy under tensile loading

The effects of strain rate on the mechanical properties,microstructure and texture of Al-Mg-Si-Cu alloy were investigated through tensile test,microstructure and texture characterization.The results show that strain rate has some influences on the mechanical properties and microstructure,but a slight influence on the texture.Overall,yield strength,ultimate tensile strength and elongation increase first,then remain unchanged,and finally increase with increasing strain rate.Independent of strain rate,microstructure in the vicinities of the fracture regions of all the specimens is composed of the slightly elongated grains.However,some differences in misorientation angle distributions can be observed.As strain rate increases,the low angle grain boundaries(LAGBs)increase first,and then decrease.Textures in the vicinities of the fracture regions are almost identical with increasing strain rate.