退火态AlCoCrFeNi高熵合金的组织演化规律及力学性能研究

为了研究热处理对高熵合金组织和力学性能的影响,文中使用真空电弧熔炼制备了铸态AlCoCrFeNi高熵合金并加以800℃和1 050℃退火处理,检测分析了合金的组织和压缩性能。研究结果表明：铸态合金组织为等轴晶形貌,等轴晶内部分为富含Ni和Al元素的树枝晶与富含Cr与Fe元素树枝晶间区域;800℃退火后合金呈现树枝晶形态,树枝晶间由于FCC相和σ相的析出导致调幅分解消失,合金的屈服强度增加、塑性降低;1 050℃退火后合金呈现等轴晶形态,晶内存在部分粗化的调幅分解相,退火处理略微降低了合金的屈服强度、而合金的塑性得到了提高。     

AlFeCuCrCoMo_x系高熵合金的组织性能

为了研究AlFeCuCrCoMo_x系高熵合金的组织性能,利用等离子弧堆焊方法制备了AlFeCuCrCoMo_x系高熵合金,并测试了其硬度、耐磨性与热膨胀性能.结果表明,高熵合金组织为枝晶和枝晶间组织.当Mo含量较低时,高熵合金主要组织为单一BCC结构.随着Mo含量的增加,其组织逐渐转变为BCC+FCC结构.当Mo含量为1. 5 mol时,高熵合金重新转变成简单BCC结构.随着Mo含量的增加,高熵合金的硬度和磨损量总体上呈现先升高后降低的趋势.当Mo含量为1. 5 mol时,高熵合金的硬度和磨损量达到最大.     

AlFeCrCoNi高熵合金的机械合金化法制备及退火行为研究

为了研究AlFeCrCoNi高熵合金的热处理工艺,文中采用机械合金化法制备了AlFeCrCoNi高熵合金,研究了球磨时间对Al、Fe、Cr、Co、Ni合金相变、晶粒尺寸、颗粒尺寸和球磨粉体形貌的影响,分析了球磨法制备的AlFeCrCoNi高熵合金的退火行为.研究结果表明:随着球磨时间的延长,晶粒尺寸逐渐减小,趋于稳定时其晶粒尺寸为34.球磨60h时,粉体颗粒形貌为球状,颗粒尺寸约为20μm.AlFeCrCoNi高熵合金在加热过程中分别在615.7℃、971.5℃和1 384.3℃出现三个吸热峰,前两个峰表明发生固态相变,1 384.3℃为高熵合金的熔点.     

FeTiNbMoW高熵合金的组织和性能

为了研究一种能够吸收γ射线的含W合金的性能,按照等摩尔比设计了一种FeTiNbMoW五组元高熵合金.利用X射线衍射仪、扫描电子显微镜、能谱仪、显微硬度计、密度仪和万能力学试验机对合金的晶体结构、微观组织、成分、硬度、密度和压缩性能进行了分析.结果表明,FeTiNbMoW高熵合金组织由简单BCC固溶体基体和分布其上的少量金属间化合物组成.BCC结构的实际晶格常数为0.315 5 nm,组织形貌为典型枝晶组织.枝晶硬度和枝晶间硬度分别为830.05和793.04 HV.合金的实测密度为10.7 g/cm3,略高于其理论值10.21 g/cm3.室温下合金的抗压强度和对应塑性应变分别为604 MPa和3.19%.合金呈粉末性断裂,其断裂机制为解理断裂.     

Zr元素对CoCrCuFeMn高熵合金组织及耐磨性能的影响

高熵合金突破以一种或两种元素作为基元的传统合金设计理念,以等摩尔比或近等摩尔比制备出具有简单相结构且综合性能优异的多主元合金,有望使金属材料的性能极限和应用空间得到进一步拓展。为了研究元素掺杂对合金物相结构、显微组织和耐磨性能的影响机理,采用真空熔炼法制备出等摩尔比的CoCrCuFeMn和CoCrCuFeMnZr高熵合金。利用XRD、OM、SEM、EDS、显微硬度计和摩擦磨损试验机测试了Zr元素添加前后CoCrCuFeMn合金的物相结构、显微组织、硬度和耐磨性。研究发现：添加Zr元素后CoCrCuFeMnZr合金的物相结构由原来的两种FCC相转变为两种HCP相,显微组织明显细化,仍为典型的树枝晶结构。两种合金的摩擦曲线都呈现先增大后降低再稳定的变化趋势,添加Zr元素后合金的摩擦因数与质量损失率分别从原来的0.57、4.14%降低到0.47、0.49%,显微硬度从219.6HV提高到983.5HV。结果表明：合金相结构发生HCP转变主要与凝固过程中易于形成富含大原子半径Zr元素的粗糙固液界面和之字型为主的HCP位向关系有关。Cu在晶间区域富集的原因在于其熔点最低、电负性最大、原子半径仅次于Zr,且与除Zr外的所有合金元素均具有相应最大的正混合焓,故而使其在凝固最晚的晶间区域聚集。Mn元素偏析系数最小是由于其熔点仅高于Cu和具有除Zr外最大的电负性差,且与Co和Zr之间存在负的混合焓,而与Cu之间具有最大正混合焓,不利于其进行长程扩散和进入领先相的点阵格位所致。Zr元素添加使合金硬度和耐磨性大幅提高则是由于细晶强化、固溶强化和相结构转变所致。     

AlCrFeNi2Cu高熵合金组织及性能x

为了分析Cu元素添加对高熵合金显微组织与微观性能的影响,采用真空电弧熔炼炉制备AlCrFeNi₂Cu_{=1.2,1.4,1.6,1.8)高熵合金,并利用扫描电子显微镜、X射线衍射仪、硬度计和压缩试验机对高熵合金的显微组织和力学性能进行测试.结果表明,AlCrFeNi2Cu=1.2,1.4,1.6,1.8)高熵合金主要由简单FCC相(富Fe-Cr相)与BCC相(富Al-Ni相)组成.随着Cu含量的增加,FCC相数量增加,组织中枝晶变得致密,但当x增加到1.8时,晶粒又变得粗大起来.Cu元素主要富集于枝晶间,随着Cu含量的增加,Cu元素呈现聚集趋势并包裹着树枝晶,当x增至1.8时,上述偏聚包裹现象更为明显.高熵合金的压缩性能和硬度均随Cu元素的添加呈现先上升后下降的趋势.当x为1.6时,高熵合金综合性能最佳,其抗压强度、屈服强度、塑性应变量和维氏硬度分别为2 256 MPa、891 MPa、35.6%和372 HV.x(x}x(x     

高熵合金在电催化氧还原反应中的应用及发展

开发用于氧气还原反应(ORR)的高效催化剂是提高燃料电池和金属-空气电池性能的关键。然而,ORR是动力学缓慢反应,存在着很高的过电势,从而降低了燃料电池和金属-空气电池的能量转换效率。高熵合金是由5种或5种以上金属元素等(近)物质的量比形成的一种新型合金材料。凭借其独特的组分与结构优势,高熵合金能够高效加速ORR、降低ORR过电势,表现出对ORR的显著催化作用。文章主要综述了高熵合金的结构、性能特点、制备方法以及在催化ORR方面的应用,并提出了挑战和发展展望。     

FeCrNiMnZrx高熵合金组织与力学性能研究

Fe27 Mn27 Ni28 Cr18高熵合金具有优异的耐腐蚀性和抗辐照性,但其屈服强度较低.为提高合金的强度,采用真空电弧熔炼炉制备了FeCrNiMnZrx(x=0,0.02,0.03,0.07)高熵合金,并对其组织及力学性能进行表征分析.研究结果表明:FeCrNiMn合金的铸态组织由富Ni、Mn的FCC基体和富Cr...     

铸态和烧结态AlCoCrFeNi高熵合金模拟海水腐蚀性能研究

为了研究铸态和烧结态AlCoCrFeNi高熵合金在模拟海水介质下的电化学腐蚀性能,采用真空电弧熔炼和放电等离子烧结工艺制备AlCoCrFeNi高熵合金,分别采用X射线衍射仪(XRD)和光学显微镜(OM)分析其相结构和微观组织,采用电化学工作站对其进行电化学试验测试.研究结果表明:AlCoCrFeNi铸态合金组织呈现等轴...     

多孔CuAlMn形状记忆合金的制备及其压缩特性

首次以NaCl颗粒为造孔剂利用烧结-脱溶法成功制备出了多孔CuAlMn形状记忆合金,并对其宏、微观形貌特征及压缩性能进行了研究.结果表明多孔CuAlMn形状记忆合金为三维贯通的开孔网络结构,孔洞分布均匀,孔的大小、形貌与氯化钠颗粒相似.多孔CuAlMn形状记忆合金试样的准静态压缩应力-应变曲线分为明显的弹性区、平台区及致密化区3个区域.长而平的平台区表明多孔CuAlMn形状记忆合金具有良好的压缩吸能特性.     

Influence of potential on structure and properties of microarc oxidation coating on Mg alloy

In order to obtain optimizing microarc oxidation coating on Mg alloy from a friendly-enviormental electrolyte free of Cr⁶⁺ and PO ₄ ³⁻ , constant potential regime was applied to produce it. The influence of potential on the morphology, composition, structure and other properties, such as microhardness and corrosion resistance were investigated by scanning electron microscopy (SEM), energy dispersive spectroscope (EDS), X-ray diffraction (XRD), hardness tester and electrochemical method. The results clearly show that oxidation potential plays an important role in the formation of coating’s structure and properties. The microarc oxidation coating is smooth and white, which consists of two layers. The external layer is loose and porous and enriched in Al and Si. Moreover, its content of Al and Si increases with the increasing operated potential. While the inner layer is compact and the content of Al and Si are lower than that of the external layer. The coating is composed of several phases and the major phases are MgAl₂O₄ and MgO, and the minor phases are Al₂O₃ and SiO₂ when the potential is higher. The microhardness of coating is obtained the maximum at the potential of 45 V, so does the corrosion resistance.     

Influence of potential on structure and properties of microarc oxidation coating on Mg alloy

In order to obtain optimizing microarc oxidation coating on Mg alloy from a friendly-enviormental electrolyte free of Cr6 and PO43-, constant potential regime was applied to produce it. The influence of potential on the morphology, composition, structure and other properties, such as microhardness and corrosion resistance were investigated by scanning electron microscopy (SEM), energy dispersive spectroscope (EDS), X-ray diffraction (XRD), hardness tester and electrochemical method. The results clearly show that oxidation potential plays an important role in the formation of coating's structure and properties. The microarc oxidation coating is smooth and white, which consists of two layers. The external layer is loose and porous and enriched in Al and Si. Moreover, its content of Al and Si increases with the increasing operated potential. While the inner layer is compact and the content of Al and Si are lower than that of the external layer. The coating is composed of several phases and the major phases are MgA12O4 and MgO, and the minor phases are Al2O3 and SiO2 when the potential is higher. The microhardness of coating is obtained the maximum at the potential of 45 V, so does the corrosion resistance.     

退火处理对La-Mg-Ni-Co合金电化学性能的影响

为了改善La-Mg-Ni-Co系贮氢电极合金的综合电化学性能，研究了退火处理对La0.7Mg0.3(Ni0.85Co0.15)3.4相结构和电化学性能的影响.在1 073 ～1 223 K下退火9 h制得样品，并进行了XRD分析以及恒电流充放电、线性极化和恒电位阶跃3种电化学测试.结果表明，铸态和退火态合金均由具有PuNi3结构的主相及少量杂相组成.退火态合金相的成分和结构均匀性得到明显改善，并具有较低的吸氢体积膨胀率.退火处理使合金的最大放电容量有所提高，循环稳定性得到明显改善.退火态合金放电容量的提高与合金中主相丰度的增大密切相关.合金循环稳定性的改善主要归结于退火态合金具有较低的吸氢体积膨胀率和较好的合金成分均匀性.     

Influence of Density on Compressive Properties and Energy Absorption of Foamed Aluminum Alloy

The foamed aluminum alloys with different densities were fabricated by melt foaming technique. The compressive properties and energy absorption of the foamed aluminum alloy with different densities were analyzed. The results reveal that the compressive stress-strain curves follow the typical behavior of cellu- lar foams with three deformation stages. Under the same strain, the energy absorption capability decreases with the decrease of density. However, with increasing the strain, the energy absorption efficiency of foamed metal increases initially and then decreases. The lower the density, the longer the plateau region, within the range of high strain, the energy absorption efficiency is always high.     

CoPt合金纳米有序阵列的制备及磁学特性

采用电化学沉积法,在氧化铝模板中制备了φ50 nm的CoPt合金纳米线的高度有序阵列.纳米线结构和磁学特性分别用透射电子显微镜、扫描电子显微镜、X射线衍射仪和振动样品磁力计测试.结果表明,CoPt合金纳米线以fcc结构存在.当外加磁场与纳米线线轴平行时,测得的矫顽力为192 Ka/m,剩磁比为0.75;当外加磁场与纳米线线轴垂直时,所测得的矫顽力仅为48 Ka/m,剩磁比为0.25.表明纳米线阵列具有明显的各向异性,纳米线的易轴方向为其线轴方向.     

Microstructures and mechanical properties of Mg-Ce-Zn-Zr wrought alloy

Microstructures and mechanical properties of Mg-2.0 ?-0.7 % Zn-0.7% Zr alloy were studied. The results of scanning electron microscopy show that Mg12 Ce phase mainly distributes at the grain boundaries. The fine Mg12 Ce phase can apparently elevate recrystallization temperature by preventing the grain boundary migration. No dynamic recrystallization occurs during the hot-extrusion. The mechanical properties of as extruded specimens are σb=278.5MPa, δ=12.0%, while those of the specimens annealed at 250℃ for 100 h are σb=272.6 MPa, δ=11.3%, which indicate that the alloy has good mechanical properties at room temperature.     

Al-Li合金挤压织构及其对性能的影响

研究了二次挤压对粉末冶金和铸锭冶金Al Li合金挤压制品织构及其对力学性能的影响.结果表明,Al Li合金经挤压轴对称变形后形成强的〈111〉,织构和弱的〈100〉织构,使合金塑韧性降低;但经二次挤压后〈111〉织构减弱,综合性能改善.文中讨论了〈111〉+〈100〉纤维织构形成的机理和变化的原因.     

Mechanical properties and tribological behavior of a cast heat-resisting copper based alloy

Mechanical properties and tribological behavior of a novel cast heat-resisting copper based alloy are investigated. The corresponding properties of a commercial aluminum bronze C95500 (ASTM B30) are compared with the alloy. The results show that the alloy possesses better mechanical properties and tribological behaviors than that of C95500 at elevated temperature. The tensile strength, elongation and hardness at 500℃ are 470MPa, 2.5% and HB220, respectively. The wear rate of the developed alloy at ambient and elevated temperature is about one-sixth and one-fortieth of that of C95500, respectively. The alloy is very suitable for ma-nufacturing heat-resisting and wear-resisting parts. Major strengthening mechanisms for the alloy are solution strengthening and the second phase strengthening.