不同冷却速度下Al-5Fe、Al-5Fe-3Y合金组织和相组成

分别采用熔炼、吸铸和单辊甩带法制备了铸态、亚快速凝固和快速凝固下的Al-5Fe合金和Al-5Fe-3Y合金,探讨了冷却速度的提高和稀土Y的添加对Al-5Fe合金的组织和相组成的影响.结果表明,稀土Y可以使Al-5Fe合金中Al3Fe相由针状转变为团球状并使快速凝固合金中出现了二次析出相.冷却速度的提高使合金的组织得到进一步细化,并使Al-5Fe和Al-5Fe-3Y合金中分别出现了亚稳相Al6Fe和金属间化合物Al10Fe2Y相.     

快速凝固制备La2Mg0．9Ni7．5Co1．5Al0.1贮氢合金的相结构及电化学性能

采用感应熔铸＋退火处理及快速凝固方法制备了La2Mg0．9Ni7．5Co1．5Al0.1贮氢合金。系统研究了快速凝固对合金的相结构、微观组织及电化学性能的影响。XRD分析表明，随着冷却速率的增加，La2Mg0．9Ni7．5Co1．5Al0.1合金的相组成发生了明显变化。退火合金由αLa2Ni7主相（Ce2Ni7型结构）和少量LaNi3相（PuNi3型结构）组成。随着冷却速率的增加，合金中出现LaNi5相（CaCu5型结构）和LaMgNi4（MgCu4Sn型结构）相，且新相的相丰度增加，aLa2Ni7相和LaNi3相的丰度减少。EPMA分析表明，快速凝固方法制备的La2Mg0．9Ni7．5Co1．5Al0.1贮氢合金为柱状晶组织且晶粒细小。合金电极的电化学测试表明，冷却速率对合金的活化性能影响不大。随冷却速率的增加，合金的最大放电容量减少、高倍率放电性能下降。在较低的冷却速率下（5m／s），合金电极的循环稳定性改善不明显，而随着凝固速度的进一步增加（20m／s），合金电极表现出较好的循环稳定性。     

Ni25Al75合金快速凝固过程中的包晶反应与凝固进程

用平面流铸技术制备了Ni25Al75合金条带，利用XRD，TEM和EDS对快速凝固后的显微组织和微区成分进行了分析。研究表明，Ni—A1合金快速凝固过程中的包晶反应受到了很大程度的抑制，从而影响到快速凝固进程，造成最终相组成中出现了平衡条件下不可能出现的α(A1)，并使NiAl3相有效合金浓度和生长速度增加，导致最终相组成中NiAl3相质量分数增加。     

冷却速度对Al-3Fe合金凝固特性和微观组织的影响

采用冷却曲线测定、光学显微镜(OM)和X射线衍射仪(XRD)研究了冷却速度对Al-3Fe合金凝固特性和凝固组织的影响。结果表明,在冷却速度为0.69~11.8℃/s的范围内,Al-3Fe合金的显微组织均由α-Al枝晶、初生富Fe相及枝晶间的共晶组织组成,其中富Fe相主要为Al₃Fe、Al₅Fe₂和Al₆Fe相。冷却速度对Al-3Fe合金的凝固特性和凝固组织有明显的影响。随着冷却速度的提高,合金初生相形核温度和共晶反应温度降低,合金的凝固组织明显细化。     

La和Nd复合添加对AZ91镁合金铸态组织和性能的影响

利用SEM和XRD等方法研究了总添加量为2.5%(质量分数, 下同)的单加或复合添加La和Nd的AZ91镁合金的铸态显微组织和相组成,并测试和分析了合金的室温力学性能。结果表明：单加或复合添加2.5%的La和Nd使AZ91合金中的β相Mg17Al12数量明显减少。单加La和单加Nd在AZ91合金中形成的稀土相分别是针状的Al11La3和块状的Al2Nd;二者复合加入时两种稀土相同时出现,Al11La3相和Al2Nd相的尺寸较单加时有所减小,其相对含量与两种稀土元素添加量成正比。当复合添加La和Nd时,Al11La3相中的部分La和Al2Nd相中的部分Nd分别被Nd和La置换。相对于单一添加,复合添加La和Nd能更显著地改善AZ91的力学性能。本实验研究的合金中,AZ91+1.0%La+1.5% Nd合金力学性能最好,其铸态合金的抗拉强度和延伸率分别为235 MPa和10%     

快速凝固制备La0.83Mg0.17Ni3.25Al0.15Mn0.1储氢合金的相结构和电化学性能

采用感应熔铸+退火处理(常规冷速)及快速凝固方法制备了La0.83Mg0.17Ni3.25Al0.15Mn0.1储氢合金.系统研究了快速凝固对合金的相结构、微观组织及电化学性能的影响.X射线衍射分析表明,冷却速率对合金的相组成影响不大,但对各相丰度影响明显.随着冷却速率的增加,合金中的LaNi5相(CaCu5型结构)丰度增加,LaNi3相(PuNi3型结构)丰度减少.EPMA分析表明,快速凝固方法制备的La0.83Mg0.17Ni3.25Al0.15Mn0.1储氢合金为扁平状晶粒组织.合金电极的电化学测试表明,冷却速率对合金的活化性能影响不大.随冷速的增加,合金的最大放电容量减小,合金电极的循环稳定性改善明显,铜辊线速度为15 m/s时容量保持率达到97.03%.     

混合稀土对超轻Mg-Li合金微观组织和力学性能的影响

本文研究了La/Ce混合稀土对Mg-9Li-3Al-xRE(x=0、0.5、1、1.5、2 w.%)合金微观组织和力学性能的影响。在加入混合稀土的铸态合金中,形成了Al4RE相,并且Mg17Al12相的含量和α-Mg相的体积分数均被减少。此外,细化了α-Mg相并提高了合金的力学性能。但是,随着La/Ce混合稀土含量的增加,Al4RE相的尺寸增大,降低了合金的力学性能。在加入混合稀土的挤压态合金中,合金中Al4RE相挤压破碎至1-3μm,分布于β-Li基体中和α/β相之间。Mg-9Li-3Al-1.5RE合金获得最好的机械性能,最大抗拉强度和延伸率分别为228.3Mpa和20.8%,同铸态Mg-9Li-3Al相比分别提高了88.6%和197.4%。     

固溶温度对Fe-24Al-La合金组织和性能的影响

为改善Fe-24Al合金的脆性,对其进行La合金化,同时对合金进行不同工艺的固溶处理。利用金相、显微硬度、压缩性能、XRD等方法研究合金铸态、固溶态的微观组织与力学性能的关系。结果表明,稀土元素La的加入使Fe-24Al合金铸态的晶粒得到了明显的细化,硬度与抗压强度有所下降,但塑性明显提升。经过固溶处理后,其相为α-Fe、FeAl相、Fe3Al相,而且经过825℃与850℃固溶处理后还出现了Fe4Al8La相。Fe-24Al-La合金抗压强度最大为1 250 MPa,但是塑性同Fe-24Al合金相比有显著提升,825℃与850℃固溶处理的塑性最好,压缩曲线最平滑,而且不存在断裂点。     

Si和Co对LaFe13-x-ySixCoy合金凝固组织和相形成的影响

采用电弧熔炼的方法研究了LaFe13-x-ySixCoy合金的凝固行为。应用XRD和SEM扫描电镜分析了合金组织结构和相组成。结果表明：La（Fe,Co,Si）13相是包晶反应生成的,Si和Co含量变化对合金的凝固行为有很大的影响,当Si含量x≤1．0、y=0-0.6时合金显微组织由α-（Fe,Si）相和共晶相组成,当x=0时共晶相La＋α-Fe,x〉0共晶相NLa（Fe,Co）Si相,α-（Fe,Si）相为主要相,随Si含量增加La（Fe,Co）Si相增多;x=1．5、y=0.2～0．6时合金显微组织由α-（Fe,Si）相、La（Fe,Co,Si）13相和La（Fe,Co）Si相组成,随Co含量增加La（Fe,Co,Si）13相增加。     

真空吸铸AZ61A镁合金的亚快速凝固行为研究

设计了真空吸铸急冷法制备镁合金小尺寸薄片铸件工艺装置,实现了镁合金AZ61A的亚快速凝固.研究分析了亚快速凝固条件下镁合金凝固态组织的特点及其亚快速凝固行为,并与常规凝固镁合金进行了比较分析.结果表明:亚快速凝固过程中,极快的冷却速率使得熔体凝固过程中固/液界面推移的速率很快、局部凝固时间很短,抑制了溶质元素扩散,使其很大程度上固溶于基体组织中;镁合金的晶粒尺寸较常规凝固试样有了明显细化,晶粒度只有几个微米,且随着冷却速率的增加,其尺寸不断减小;提高了铸件成分及组织的均匀性,凝固态组织中析出的3-Mg17Al12相极少甚至消失,最终形成以过饱和c-Mg固溶体为主相的亚快速凝固组织.     

Microstructure evolution and mechanical behavior of as-cast,heat treated and directionally solidified Fe–15Al–10Nb alloys

Fe–15Al–10Nb (at.%) alloys containing Laves phase fibers embedded in a disordered α-(Fe,Al) matrix were investigated in as-cast, heat treated and directionally solidified condition. Microstructure consisted of either duplex structure of primary dendrites and eutectic (as-cast and heat treated) or fully eutectic structure (directionally solidified). Nanoindentation on the Laves phase fibers revealed their anisotropic features as well as the onset of dislocation plasticity. Compression testing showed the yield strength anomaly, which occurred in the 500–650 °C range. Directional solidified alloy exhibited the lowest strength fracture toughness whereas the as-cast alloy had the highest strength and fracture toughness. The value of stress exponent obtained from the strain rate dependence of the flow stress indicated that the dislocation climb mechanism dominated the creep process. Deformation mechanisms were also discussed and related to the microstructure evolution.     

Relationship between cooling rate and electrochemical performance of melt-spun AB_5 alloy

1　INTRODUCTIONNi/MHsecondarybatterieshaverapidlybeendevelopedandgraduallysubstitutedforNi/Cdbatter iesintherecentdecadeduetoitshighspecificenergydensityandhavingnopoisonouselementcadmium .TheactivematerialofnegativeelectrodewidelyusedinNi/MHsecondarybatteriesisAB5 typehydrogenstoragealloynowadays .However ,itisstillneededtoimprovethecomprehensive propertiesofAB5 typehydrogenstoragealloyforprolongingtheservicelifeofNi/MHbatteries .Anormalmethodtoimprovethecomprehensivepropertiesofthe…     

铜模铸造块体Fe-Ga合金的磁致伸缩性能和结构特征(英文)

采用惰性气体保护下的感应熔炼铜模吹铸方法,制备具有非平衡快速凝固组织、晶粒沿温度梯度取向生长的Fe100-xGax(x=16～20)合金棒。XRD分析判定棒材主要为无序A2相结构且具有110轴向择优取向。随着Ga元素含量的增加,合金的饱和磁化强度明显降低,低场动态响应迅速增加。快速凝固获得的 Fe82Ga18合金棒的纵向饱和磁致伸缩在30kA/m磁场强度下为92×10-6。吹铸法制备的Fe100-xGax(x=16～20)合金棒材大的磁致伸缩性能源自快速凝固过程中所保留下来的高温无序A2相和合金内部所具有的大量沿100方向排列的短程有序富Ga原子团簇,这些富Ga团簇最终诱发畸变 DO3相的生成,正如(200)衍射峰发生劈裂所示。有序化转变生成的DO3相对该合金的磁致伸缩性能不利。     

Effect of rapid solidification on the structural and electrochemical properties of the Ti–V-based hydrogen storage electrode alloy

The structural and electrochemical properties of the as-cast and rapidly solidified Ti_0.8Zr_0.2V_2.4Mn_0.48Cr_0.72Ni_0.9 alloys were studied. Both the as-cast and the rapidly solidified alloys were mainly composed of a C14 Laves phase matrix with hexagonal structure and a V-based solid solution phase with body centered cubic (BCC) structure. The V-based solid solution phase showed very fine dendrites in the rapidly solidified alloy instead of the large dendrites as observed in the as-cast alloy. In addition, the content of the C14 Laves phase in the alloy decreased greatly after rapid solidification. Electrochemical measurements indicated that the rapidly solidified alloy had a lower discharge capacity, a slower activation rate, a worse high rate dischargeability, a smaller exchange current density and limiting current density, but an improved cycle life compared with that of the as-cast alloy.     

Microstructure and mechanical properties of Al-5.5Fe-1.1V-0.6Si alloy solidified under near-rapid cooling and with Ce addition

Al-Fe-V-Si alloys were developed for use at elevated temperature and usually produced through a rapid solidification-powder metallurgy route. In this work, effort was made to produce the material via casting route. The studied alloys were cast under the condition of near-rapid cooling. The influence of Ce addition on microstructure and mechanical properties of near-rapid solidified alloys were investigated. The results indicate that the as-cast microstructure of Al-5.5 Fe-1.1 V-0.6 Si alloy is significantly refined when the alloy was solidified under nearrapid cooling. Adding Ce results in the further refinement of intermetallic compound and the formation of an Al-V-Ce phase which replaces the primary phase Al_(13)(Fe,V)_3 Si. The mechanical properties of the alloy are significantly improved by Ce addition: More than 70% increase in tensile strength and elongation is achieved by adding 1.00 wt% Ce to the alloy. It is concluded that near-rapid cooling and Ce addition are effective in improving mechanical properties of cast Al-5.5 Fe-1.1 V-0.6 Si alloy.     

水玻璃砂型铸造Fe_3Al金属间化合物的组织和力学性能

研究了中频感应炉熔炼、水玻璃砂型冷却制备的Fe3A1金属间化合物合金铸态及热处理后的组织、力学性能和冲击断裂行为。结果表明:热处理后合金的抗拉强度σb提高了49MPa,硬度由铸态时的21.6HRC提高到了25HRC,但合金的冲击韧度出现了较明显的下降;铸态时合金的断裂主要呈沿晶断裂特征,热处理后合金断口呈沿晶+穿晶的混合型断裂特征。     

微合金化元素Zr对5083铝合金组织和性能的影响

在实验室中用井式坩埚炉熔炼铸造了5083和5083+0.1Zr两种铝合金,轧制后在100～450℃范围内退火。通过金相显微镜、显微硬度计、扫描电镜、电子万能试验机、透射电镜对合金的铸态组织、板材纤维组织、力学性能、耐蚀性能、第二相粒子成分进行了分析,研究了微量元素Zr对5083铝合金组织性能的影响。结果表明,添加微量元素Zr能够细化合金组织,与未添加Zr相比,添加0.1Zr的5083合金的铸态晶粒尺寸从123μm降至73μm,并使第二相粒子Al₆Mn(Fe)尺寸变小;同时使晶间腐蚀坑变小,合金耐蚀性得到提高。添加微量元素Zr还能抑制合金板材再结晶,300℃退火1 h无明显再结晶现象;尤其是5083+0.1Zr合金经250℃退火1 h,抗拉强度为389.50 MPa,屈服强度为215.62 MPa,伸长率为18.2%,仍完全满足使用要求。     

CRYSTAL STRUCTURE AND MICROSTRUCTURE OF RAPIDLY SOLIDIFIED La(Ni, Sn)（5+x）(x=0.1---0.4) HYDROGEN STORAGE ALLOYS

采用常规熔铸和单辊快凝制备了CaCu5型贮氢合金La(Ni,Sn)5 x(x=0．1—0．4),用X射线衍射及扫描电镜分析了合金显微形貌、纳米晶粒和晶体结构的特征及相互间关系．XRD Rietveld分析表明,常规熔铸方法制备的La-Ni-Sn三元合金含有数量较多的沿C轴定向排列的Ni-Ni“哑铃”对,其纳米级晶粒呈扁平状,电镜观察显示该合金具有粗大的树枝状形貌,除La-Ni-Sn三元合金外,在熔铸合金中尚有一定量的LaNi5合金和单质Sn存在．单辊快凝制备的合金随着冷凝速度的加快,合金的纳米级晶粒沿(001)晶面法线方向明显变长,但沿(100)晶面法线方向的尺寸长大较慢,在高快凝速率下(10,15,20m／s),合金的显微形貌由细小的柱状与等轴状晶块组合而成．     

混合稀土对金银铜合金组织及硬度的影响

为研究混合稀土元素在金银铜合金内部的分布状态以及混合稀土元素的添加对金银铜合金硬度的影响,使用真空中频感应炉制备了Au-35Ag-5Cu、Au-35Ag-5Cu-1RE合金,并对铸态合金进行不同变形量的轧制加工,探讨了稀土元素的添加、变形量对合金组织及维氏硬度的影响。使用EDS进行了稀土元素分布检测、DSC分析固液相线温度并进行维氏硬度的测量等。结果表明,稀土元素La、Ce、Pr、Nd占据了Au、Ag元素的位置,改变了AuAg两种元素的分布,与Cu固溶效果较好,对Cu元素分布没有显著影响。稀土元素的添加降低了Au-35Ag-5Cu的液相线温度和固相线温度,增大了液相线温度和固相线的温度差。混合稀土元素的添加有助于提高铸态及轧制态金银铜合金的耐磨性。     

The oxidation of a directionally solidified cobalt-tungsten eutectic alloy

A study of the oxidation of directionally solidified Co-W alloys were performed at 750, 900, and 1050°C. The study involved a comparison of the oxidation behavior of directionally solidified and as-cast alloys along with the oxidation behavior of the pure components. The study incorporated both thermogravimetric kinetic measurements and morphological studies of the oxides as a function of both temperature and time. Differences were noticed in both the oxidation rate and the oxide morphology and were attributed to differences in alloy microstructure. The directionally solidified Co-W alloy was found to be more spall resistant but also oxidized more rapidly than the conventionally as-cast alloy. Both alloys were more oxidation resistant than the pure components.