Gd对Al-Zn-Mg-Cu-Zr合金组织与力学性能的影响

通过铸锭冶金工艺,制备了6种不同Gd含量的A1-Zn-Mg-Cu-Zr-Gd合金。采用金相观察、力学性能测试、扫描电镜及透射电镜等分析手段,研究了质量分数分别为0%、0.1%、0.15%、0.2%、0.25%、0.3%的Gd对基体合金的铸态及时效态显微组织和力学性能的影响。结果表明,Gd对于A1-Zn-Mg-Cu-Zr合金的组织、性能的影响显著:Gd含量在小于0.25%范围内时,随含量增加细化效果、强度以及伸长率都得到增加;当Gd含量为0.25%时,铸态组织中基体晶粒最小,达到32μm左右;T6态合金组织的强度、伸长率达到最优,抗拉强度达到624.54MPa,屈服强度达到595.00MPa,伸长率为13.3%,且固溶组织具有良好的抗再结晶作用;而当Gd含量超过0.25%时,合金的的组织与性能产生恶化。     

Gd对Mg-2Al-Zn合金微观组织及力学性能的影响

研究了稀土Gd的添加对铸态Mg-2Al-Zn合金显微组织和力学性能的影响。结果表明,Mg-2Al-Zn-xGd合金由α-Mg和Al2Gd两相组成,Al优先与Gd反应生成Al2Gd,且合金中Al2Gd的数量和形态受Gd的添加量影响。弥散分布的Al2Gd使合金室温力学性能得到显著提高,在Gd的添加量(质量分数)为2%时,抗拉强度和屈服强度分别达到252MPa和135MPa。但Gd的添加量达到3%时,Al2Gd相尺寸变大、数量过多,导致合金的力学性能迅速下降。颗粒状和针状Al2Gd在晶界上或基体上的团聚导致合金由韧性断裂转变为解理断裂。     

稀土元素Gd对NiAl合金显微组织和力学性能的影响

研究了不同Gd含量对二元NiAl合金组织以及室温和1100 ℃压缩性能的影响.结果表明,稀土Gd在NiAl中的固溶度很小,在合金晶内及晶界大量析出一种脆硬的新相--富Gd相.由于Gd的固溶强化和适量富Gd相产生的第二相强化,使得含0.10Gd合金的室温压缩强度高于二元NiAl的,而晶界上析出较多的富Gd相又使得含0.25Gd和0.50Gd合金的室温压缩强度较低;Gd的净化基体作用使得NiAl-Gd合金的室温压缩塑性高于二元NiAl的室温压缩塑性.含Gd合金在1100℃压缩,亦未出现应变软化现象.     

稀土元素Gd对NiAl合金显微组织和力学性能的影响木

研究了不同Gd含量对二元NiAl合金组织以及室温和1100℃压缩性能的影响．结果表明,稀土Gd在NiAl中的固溶度很小,在合金晶内及晶界大量析出一种脆硬的新相——富Gd相．由于Gd的固溶强化和适量富Gd相产生的第二相强化,使得含0．10Gd合金的室温压缩强度高于二元NiAl的,而晶界上析出较多的富Gd相又使得含0．25Gd和0．50Gd合金的室温压缩强度较低;Gd的净化基体作用使得NiAl-Gd合金的室温压缩塑性高于二元NiAl的室温压缩塑性．含Gd合金在1100℃压缩,亦未出现应变软化现象．     

Gd对ZL205A合金显微组织和力学性能的影响

研究了不同质量分数Gd对ZL205A合金铸态及T6态显微组织和力学性能的影响.采用光学显微镜、荧光光谱仪和电子探针对制备的试样微观组织和元素分布进行分析,并利用电子拉伸试验机对铸锭的力学性能进行测试.结果表明:微量稀土元素Gd能细化ZL205A合金的晶粒,并与合金中的其他元素形成新相,能提高合金铸态和T6后的力学性能;当Gd加入量为0.06％时,综合力学性能最优,铸态时抗拉强度为192MPa,伸长率为11.1％;T6态时抗拉强度达到421.1MPa,伸长率为10.2％.但当Gd添加量过多时,合金的组织与性能均产生恶化.     

Sc对Al-Zn-Mg-Cu-Zr合金铸态组织和力学性能的影响

采用金相显微镜、扫描电镜和能谱分析,研究Sc对Al-9.0Zn-2.5Mg-2.5Cu-0.15Zr合金铸态组织和力学性能的影响。结果表明,添加0.20%-0.60%的Sc,会使合金的铸态组织由粗大的树枝晶变为等轴晶,并使Cu的偏聚减轻,且Sc含量越高,合金铸态组织越细,Sc含量为0.60%的合金铸态组织最细小;随着Sc含量的增加,合金的抗拉强度升高,T6态时,Sc含量为0.60%的合金抗拉强度高达783.9 MPa。从熔体中析出的Al3（Sc,Zr）一次粒子具有与α（Al）基体相同的FCC晶格,晶格常数接近,可有效地细化合金的铸态组织。合金强化机理主要为Al3（Sc,Zr）引起的细晶强化、亚结构强化和沉淀强化。     

Al-Cu-Ce合金的微观组织与力学性能

采用X射线衍射、金相显微镜、扫描电镜、能谱分析及拉伸性能测试等方法,研究3种成分Al-Cu-Ce合金的显微组织与力学性能。结果表明:铸态Al-14Cu-7Ce合金由α-Al+Al8CeCu4片状共晶组成,而Al-10Cu-5Ce、Al-18Cu-9Ce合金中除含有α-Al+Al8CeCu4共晶组织外,还分别含有α-Al和Al8CeCu4初生相。铸态Al-14Cu-7Ce合金具有优良耐热性能,即使550℃×3 h退火后仍能保持约360 MPa的抗拉强度,退火导致合金强度下降的主要原因是高温下共晶Al8CeCu4相的球化。经充分球化退火后,Al-Cu-Ce合金能获得良好的热轧、冷轧变形能力,并且变形态合金也具有良好的耐热性能,因而Al-Cu-Ce合金有望成为一种兼具铸造和变形两用的新型耐热铝合金。     

Mg—Gd—Ag—Zr合金的组织与力学性能

对Mg-18.6Gd-1.9Ag-0.24Zr合金铸态、T4态和T6态的显微组织和力学性能进行了研究.结果表明,该合金铸态时由α-Mg与分布在晶界的Mg5Gd相组成;T4态时由过饱和α-Mg固溶体和H2Gd相组成;峰值时效态的析出相为β相.该合金具有明显的时效强化效果,在200、225、250℃温度下的时效处理结果发现,随着时效温度的升高,合金的峰值时效硬度下降,到达峰值硬度的时间大为缩短.其中200℃下的峰值时效硬度(HV)最高,达到了134.合金经过200℃的峰值时效处理后具有最高的室温力学性能,屈服强度、抗拉强度和伸长率分别为291.0 MPa、383.5 MPa和1.17%.     

微量Ga对A356合金微观组织及力学性能的影响

研究了微量Ga对A356合金的微观组织和力学性能的影响.结果表明,Ga含量的增加(0.02%～0.06%),对均匀化退火后A356合金室温抗拉强度影响不明显,在673 K时抗拉强度提高14.5%,但Ga的加入显著降低合金的伸长率,且伸长率随着温度的增加而降低.Ga对T6处理后的强度略微提高,伸长率有所降低,但对合金高温抗拉强度和伸长率的影响作用效果明显,能大幅度提高高温抗拉强度,同时降低了合金的伸长率.     

Mg含量对Al-Cu-Mg-Ag合金组织与力学性能的影响

通过室温拉伸、疲劳裂纹扩展速率测试及透射电镜等实验手段,研究Mg含量对Al-Cu-Mg-Ag合金时效析出过程与力学性能的影响。结果表明:随着Mg含量的增加,合金的时效响应速率加快,而强度则先上升后下降,当Cu/Mg比为6时,合金强度最高;Mg含量的提高为主要析出相?相提供了更多的形核位置,使得合金基体中的析出相细小弥散,分布均匀;Cu/Mg比接近4的合金经165℃时效30min处理后,晶内析出大量的Cu-Mg原子团簇,疲劳性能最佳。     

Effect of Gd content on microstructure and mechanical properties of Mg-Y-RE-Zr alloys

Four kinds of Mg-Y-RE-Zr alloys with different Gd contents were prepared,and the effect of Gd content on microstructure and mechanical properties of the alloys was researched.Based on the experimental investigation,the compounds at the grain boundaries are mainly Mg_(24)Y_5,Mg_(41)Nd_5,and Mg_5Gd phases.The average grain size of as-cast alloys is 50-60μm.After T4(535℃, 24 h)treatment,Mg_5Gd phases mostly decompose and dissolve into the matrix,and the disperse spotted phases are mainly Mg_(24)Y_5 and Mg_(...     

Effects of Y content on microstructures and mechanical properties of as-cast Mg-Zn-Nd alloys

The effects of Y addition amount on the microstructures and mechanical properties of as-cast MgZn-Nd alloy have been investigated by using an optical microscope, a scanning electron microscope, backscattered electronic imaging technique, an X-ray diffractometer, a differential thermal analyzer and a universal testing machine. There are three kinds of ternary phases in the Mg-Zn-Y system alloys, such as I phase(Mg3Zn6Y), W phase(Mg3Zn3Y2) and Z or X phase(Mg12Zn Y). The experimental results in the present study indicate that the Mg-Zn-RE(RE includes Y and Nd) ternary phases change from the I + W phases in turn to unique W, W + Z and unique Z as the Y content increases from 0% to 3%. Simultaneously, their distribution gradually changes from small particle-like form to continuous network form. The grain size first decreases as the Y content increases from 0% to 1% Y, then increases when the Y content exceeds 1% and finally decreases again when the content exceeds 3% due to the variation of growth restriction factor caused by the increased Y element and the change of the ternary phases. The hardness continuously increases because of the increased ternary phase amount. The ultimate tensile strength and elongation first increase within the range of 0-1% Y, also due to the increased ternary phase amount and grain refinement, and then decreases because of the grain coarsening, porosity formation and continuous network distribution of the ternary phases. The grain bonding strength of the W phase-containing alloys is quite strong and the W phase is an ideal strengthening phase if a given amount of it distributes in discontinuous and small-sized form. The alloy with 1% Y only has one ternary phase of W, but has the best combination of mechanical properties. The fracture regimes of these alloys always present a transgranular mode.     

Cu含量对Al-Mg-Si-Cu合金微观组织和性能的影响

采用DSC热分析、硬度、电导率、拉伸和晶间腐蚀等测试及透射电镜组织观察,研究Cu含量对Al-Mg-Si-Cu合金微观组织和性能的影响。实验表明:180℃时效时,4种合金硬度上升至峰值后持续下降,且随着Cu含量增加,合金的时效硬度随之提高,硬化速率加快而软化速率降低;时效时电导率先下降至最低值后又持续上升,且Cu含量越高,电导率越低。随着Cu含量增加,T6和T4态合金的强度随之提高,晶间腐蚀抗力下降,但无Cu合金不发生晶间腐蚀;T6态合金析出相类型随Cu含量增加而变化,Cu含量较低时(0.6以下),析出β″相;而Cu含量为0.9时,析出相为β″相和Q′相共存;且随着Cu含量增加,析出相数量和体积分数增加而尺寸减小,T4态合金析出相为原子团簇。     

钆对Mg-8Li-4Zn-xGd合金铸态组织与力学性能的影响

采用锂盐熔剂保护熔铸Mg-8Li-4Zn-xGd(x=1,3,5)合金铸锭,研究钆含量对铸态合金组织和力学性能的影响。结果表明:Mg-8Li-4Zn-xGd合金基体由α-Mg(HCP)和β-Li(BCC)双相构成。随着钆含量的增加,Mg₅Gd共晶相和Zn₁₂Gd化合物相逐渐连成网状,将基体α+β双相隔离成20～40μm的等轴状或类似于铸铁中的共晶团状,可有效细化α-Mg相和连续的β-Li相;组织中大颗粒Mg₂Zn₁₁相弥散分布在β-Li相内,Mg₅₁Zn₂₀相分布在α-Mg晶界处;锌元素还可以在β-Li相中析出细小弥散分布的MgZn相,其数量随钆含量的增加而增加,可直接弥散强化β-Li相。此外,锌和钆对合金硬度的影响较大,随着钆含量的增加,合金的抗拉强度提高,但伸长率降低。     

Effects of electromagnetic field intensity on as-cast microstructures and mechanical properties of Al-Zn-Mg-Cu-Zr alloy

Al-Zn-Mg-Cu-Zr ingots with diameter of 200 mm were made by low frequency electromagnetic casting （LFEC） and conventional direct chill （DC） casting process. The results show that under the low frequency electromagnetic field （25 Hz, 32 mT） the microstructures of LFEC ingot from the border to the center on the cross section are all equiaxed grains, and the grains are much finer and more uniform than that of DC ingot. The magnetic flux density plays an important role in the microstructure formation of LFEC ingots. With increasing the magnetic flux density from 0 mT to 32 mT, grains become finer （from about 120 μm to 30 μm） and more uniform. While, with increasing the magnetic flux density from 32 mT to 46 mT, the grains change much slowly. In the range of experimental parameters, the optimum magnetic flux density for LFEC process is found to be 32 mT.     

Sr对AZ91镁合金组织及力学性能的影响

采用光学显微镜、扫描电子显微镜和X射线衍射仪等研究Sr对AZ91镁合金组织及力学性能的影响.结果表明:添加微量Sr可以细化并离散AZ91合金的铸态共晶组织,在合金晶界处Sr与Al生成多角块状或杆状的Al4Sr高熔点相;当Sr含量为0.2%时,AZ91-0.2Sr合金的综合力学性能最优,AZ91-Sr合金的时效进程与AZ91合金相比明显被抑制.由于这些析出相及合金晶界附近Al4Sr高熔点相的强化作用,AZ91-0.2Sr合金经T6处理后的室温和高温力学性能皆优于原AZ91合金的.     

Sc微合金化对Al-Zn-Mg-Cu-Zr合金组织性能的影响

采用铸锭冶金法制备了Al-8.0Zn-2.0Mg-1.2Cu-0.15Zr-xSc合金,对合金进行了固溶、时效处理,测试了不同状态下合金的力学性能和电导率,利用光学显微镜、扫描电镜和透射电子显微镜研究了合金不同状态的显微组织。结果表明:添加微量钪形成的一次Al3(Sc,Zr)相可作为异质形核核心,细化合金铸态组织;均匀化退火过程中析出的二次Al3(Sc,Zr)粒子强烈钉扎位错和亚晶界,有效阻碍固溶处理过程中合金的再结晶;含0.30%Sc的Al-Zn-Mg-Cu-Zr合金的抗拉强度和伸长率显著高于不加钪的铝合金,经一般固溶及回归再时效(RRA)处理后含0.30%Sc合金的抗拉强度提高36 MPa、屈服强度提高30 MPa、伸长率提高3.0%;采用470℃×60 min+485℃×60 min强化固溶处理,降低合金固溶态的电导率,将合金固溶态以及T6态的抗拉强度分别提高了79.6 MPa、55.8 MPa。     

Effect of Sc and Zr on microstructures and mechanical properties of as-cast Al-Mg-Si-Mn alloys

Microstructures of as-cast Al-Mg-Si-Mn alloys with and without Sc and Zr were investigated by optical microscopy, scanning electronic microscopy(SEM) and energy dispersion spectrum analysis. Addition of 0.2%-0.4% Sc can refine the grain size and change the growth morphology from dendritic to fine equi-axial crystal. The higher the addition of Sc, the finer the as-cast grain size. The tensile strength is increased by more than 30% with 0.4% Sc. Moreover, an addition of 0.1%-0.2% Zr is able to refine grain size and change the growth morphology from dendritic to equi-axial grain too, but less effective. However, Zr is found to increase the ductility of the cast alloys, and the elongation is increased to 11.97% with 0.2% Zr.     

Nd添加对AZ80镁合金显微组织及力学性能的影响(英文)

研究添加稀土元素Nd对AZ80镁合金显微组织及力学性能的影响。结果表明:添加1.0%Nd元素可以有效地改善AZ80合金的铸态组织,其晶粒尺寸由448μm细化至125μm,凝固组织中出现条状的Al11Nd3相和块状的Al2Nd相,且β-Mg17Al12相显著细化,由连续网状变为不连续分布。时效过程中Nd元素的添加抑制了晶界处不连续析出相的出现,并推迟合金时效峰值的出现。在AZ80合金中添加1.0%Nd时,合金的综合力学性能最佳,屈服强度、抗拉强度和伸长率分别为103.7MPa、224.0MPa和8.4%。该合金T6态的屈服强度和抗拉强度分别达到141.1和231.1MPa。