Decomposition processing and precipitation hardening of rapidly solidified Al-Cr-Y-Zr alloy

1　ＩＮＴＲＯＤＵＣＴＩＯＮＦｏｒｌａｓｔｔｗｏｄｅｃａｄｅｓｒａｐｉｄｌｙｓｏｌｉｄｉｆｉｅｄＡｌ Ｃｒ Ｚｒ( Ｍｎ)ｈｅａｔ ｒｅｓｉｓｔａｎｔａｌｕｍｉｎｕｍａｌｌｏｙｓｙｓｔｅｍｈａｓｂｅｅｎｐａｉｄａｐｕｂｌｉｃａｔｔｅｎｔｉｏｎｂｅｃａｕｓｅｏｆｉ     

STUDY OF MICROSTRUCTURE IN AN Au-Ni-Fe-Cr-In-Zr ALLOY

The microstructure of an AuNiFeCrInZr alloy has been,studied by means of TEM,CBED,SEM and EDS.The results show that the alloy contains Au-rich solid solution,Ni-richsolid solution,and η-and ω-phases,The η-phase containing 90at%Cr possesses anorthorhombic structure with a=0.448nm.b=1.40nm and c=1.21nm,and space group ofPmm2 or Pmmm.The ω-phase is an fce structure with a=0.682nm and space group ofFm3m.The ω-phase dispersed in the alloy matrix plays an important role in increasingstrength and wear resistance of the alloy.     

Crystal structure and thermal stability of martensite in Cu-24Al-3Mn alloy

1　ＩＮＴＲＯＤＵＣＴＩＯＮＣｕ ｂａｓｅｄｓｈａｐｅｍｅｍｏｒｙａｌｌｏｙｓ (ＳＭＡ )ｗｅｒｅｓｔｕｄｉｅｄｂｙｍａｎｙａｕｔｈｏｒｓｉｎｒｅｃｅｎｔｙｅａｒｓ[1～ 13 ] .Ｉｔｉｓｃｏｎｖｉｎｃｅｄｔｈａｔｔｈｅｓｈａｐｅｍｅｍｏｒｙｅｆｆｅｃｔｉｓａｓｓ     

Metallography of a melt-quenched aluminum-cobalt alloy

Rapid quenching from the melt of an Al-5 wt.% Co alloy has resulted in the formation of a supersaturated solid solution at very high cooling rates as obtained in the gun technique. With decreasing cooling rate (and increasing thickness of the specimen), e.g., in melt-spun condition, a variety of microstructures has been produced consisting of fine dendritic patterns, cellular-dendritic structures, and precipitation of coarse intermetallic particles. Two metastable phases have also been detected—one with a bcc structure and a = 0.286 nm corresponding to β-AlCo, and the other having an fcc structure with a lattice parameter a = 0.52 nm. Electron microscopy, electron diffraction, and x-ray microanalysis have been extensively employed to fully characterize the phases present in the melt-quenched alloy.     

快速凝固Al－8．32Fe－3．4Ce合金中弥散合金相的TEM测定

用常规电子显微术及ＥＤＡＸ能谱分析方法，对压制的快速凝固Ａｌ－８．３２Ｆｅ－３．４Ｃｅ合金热暴露过程中存在的弥散合金相进行了测定，确定出一种新相属于三角晶系，点阵常数为ａ＝１．ｎｍ，ｃ＝０．７ｎｍ（用六角点阵表示），ＥＤＡＸ能谱定量分析表明此相相组成约为Ａｌ_８Ｃｅ。     

BEHAVIOUR OF Co_5Cr_3Si_2 PHASE IN Cu-RICH ALLOYS CONTAINING Co,Cr AND Si

The major phases in the Cu-rich alloys containing Co,Cr and Si are α-Cu(a solid solutionof Co,Cr and Si in Cu),χ-phase(Co_5Cr_3Si_2)and Co_2Si.In comparison with referencesample,it has been detected that the crystal structure of Co_5Cr_3Si_2 is cubic,α-Mn type witha=0.8694 nm.The melting temperature of χ-phase and the alloy are higher than that of thepure Cu,namely,1535 and 1389 K respectively.During ageing treatment,the Co_2Si phaseprecipitates out from α-Cu and χ-phase simultaneously,but the hardening effect is mainlycontributed by the precipitation from α-Cu.     

Microstructure and transformation behavior of Ni50Ti45Ta5 shape memory alloy

1　INTRODUCTIONTheNiTishapememoryalloy (SMA )iscur rentlyatopicofnotableinterestinmedicine .Itpro videsauniqueopportunitytomakenovelsurgicalim plantsandinstrumentsforminimallyinvasive ,vascu larandorthopedicsurgery .Recently ,NiTiimplantshavebeendevelopedforcardiovascularandgastroin testinalsurgery[13] .ThehighnickelcontentofNiTi(5 4%bymass)cancauseproblemsinbiocompati bilitybecauseoftoxiceffectsofnickel[4 ] .Moreover ,thelowX rayvisibilityofNiTiSMAhaslimitedsomemedicalapplications …     

Preparation of isotropic Sm2Fe17Nx magnetic powders and their bonded magnets

The isotropic Sm2Fe17Nx magnetic powders were prepared by Hydrogenation-Disproportion-Desorption-Recombination (HDDR) process. The phase and microstructure evolutionary process of Sm-Fe alloy during the solidification, homogenization, HDDR and nitration processes were investigated by means of XRD, SEM, EDX and AFM. The results show that the homogeneous Sm2Fe17 alloy wassuccessfully obtained and the impurity phases and residual stress were well removed by heated at 1050 ℃ for 24 h. When heated at 800 ℃ for 1h in H2 of 0.1 Mpa, the alloy turns into SmHx and α-Fe with plenty of nanocrystals. After vacuumized at 800 ℃ for 2h the alloy recombines into Sm2Fe17 with a crystal grain size of about 85 nm.The lattice constant of the alloy increases and the expanding of the crystal cell reaches 6.28% after nitrified at 500 ℃ for 5 h. The magnetic property of isotropic bonded Sm2Fe17Nx magnets is Br=0.6704 T, Hcj = 1015 kA·m-1,( BH )max =73.7 kJ·m-3 with a density of 6.04 g·cm-3 .     

Refining performance of Al–3Ti–0.2C–5Sr on A356 alloy and electron microanalysis of ternary Al–Ti–Sr phases

The effect of Al-3Ti-0.2C-5Sr(wt%) grain refiner on the refining performance and modification of A356 alloy was investigated using optical microscope(OM).The morphology and crystal structure of ternary Al-Ti-Sr phases in Al-3Ti-0.2C-5Sr refiner were analyzed by scanning electron microscopy(SEM) and transmission electron microscopy(TEM).The results show that the ternary Al-TiSr phases in Al-3Ti-0.2C-5Sr refiner can promote the grain refining efficiency of A356 alloy.The ternary Al-Ti-Sr phases co-exist in two morphologies,i.e.,blocky-like phase and surround-like phase,besides,which both have the same chemical composition of Al_(34)Ti_3Sr.The crystal structure of Al_(34)Ti_3Sr is face-centered cubic,and the lattice parameter is determined to be about 1.52 nm.     

Ti添加对快淬Pr基永磁合金磁性能与显微结构的影响

采用快淬法制备了Pr基(Nd,Pr)10.5Fe81.5-xTixCo2B6(x=0.0,1.0,2.0,3.0,4.0,5.0)系列粘结磁体,研究了添加Ti元素对快淬合金显微结构和磁性能的影响。Ti元素能有效细化合金的晶粒,添加3at%Ti的合金,晶粒细化到约70nm,且大小均匀;添加量超过3at%,晶粒进一步细化,但均匀性变差。含Ti3at%的(Nd,Pr)10.5Fe78.5Ti3Co2B6合金,粘结磁体磁性能达到最佳值,Br=0.655T,Hci=681kA/m,(BH)m=68kJ/m3。Ti元素低于3at%,合金晶粒粗大,磁性能较低;超过3at%后,富Ti的晶间相加厚,晶粒间的交换作用和剩磁增强效应减弱,且晶粒大小不均匀,合金的内禀矫顽力虽然增加,但剩磁Br和最大磁能积(BH)m降低。     

Zr55Al10Ni5Cu30块状非晶合金靠近玻璃转变点的等温纳米晶化

研究了Zr55Al10Ni5Cu30块状非晶合金靠近玻璃转变点等温晶化过程。结果表明：420℃退火5h,出现了尺寸为20nm左右的晶相,同时,非晶基体也出现了尺寸为1－2nm分布均匀的团簇状结构;退火10h,析出的晶相尺寸为20－50nm,所占的体积分数为40％;退火20h之后,非晶相完全转变为亚稳相,析出的晶相尺寸为50nm左右,并没有出现明显的长大现象。退火得到的晶相为Cu10Zr7,Zr2Ni及一些未能标定的相,这些相在420℃具有相对的稳定性,没有问题稳定相转变。退火后,残余非晶相的热稳定性降低。等温退火过程经历了从非晶相→团簇状结构→亚稳相的转变过程。     

Crystal structures and hydrogenation behavior of （Ca0.9Sr0.08（Al1-xZnx）3 alloys

The crystal structures and hydrogenation behavior of the （Ca0.9Sr0.1）8（Al1-xZnx）3 （x = 0, 0.1, 0.2, 0.3 and 0.4） alloys were investigated. The new phase （Ca,Sr）E（Al,Zn） was found whenx 〉 0.1. （Ca, Sr）E（Al,Zn） crystallizes in space group 14/mmm （A-139）. The lattice parameters were calculated to be a = b = 1.1616（2） nm, c = 1.6422（4） nm. Zn atoms occupy the 8h and 16n sites together with Al atoms. The （Ca0.9Sr0.1）8Al3 alloy only contains a single Ca8Al3 phase. The （Ca0.9Sr0.1）8（Al1-xZnx）3 alloys consist of Ca8Al3, CasZn3, Ca and （Ca,Sr）2（Al,Zn） phases when x is from 0.1 to 0.3. As x increasing to 0.4, the alloy consists of （Ca,Sr）E（Al,Zn）, Ca8Zn3 and Ca. The hydrogenated （Ca0.9Sr0.1）8Al3 and （Ca0.9Sr0.1）8（Al0.9Zn0.1）3 samples consist of CartE and Al. The （Ca0.9Sr0.1）8（Al1-xZnx）3 （x = 0.2, 0.3 and 0.4） samples can be hydrogenated into CaH2, Al and CaZnl3 under a hydrogen pressure of 5 MPa at 473 K.     

六方Al14.2(Fe,V)3.0Si1.3准晶近似晶体相的电子衍射分析

利用选区电子衍射和会聚束衍射研究了喷射沉积Ａｌ－Ｆｅ－Ｖ－Ｓｉ合金中一种六方相的晶体结构,其点阵常数为：ａ＝２．５２ｎｍ,ｃ＝１．２６ｎｍ,空间群为Ｐ６／ｍｍｍ。该六方相与立方相具有固定取向关系,且ＥＤＳ分析表明,两相成分相近。系统对比分析ＳＡＥＤ花样发现,六方相的某些带轴衍射谱具有立方相的二十面本结构基元表现出的衍射特征。表明六方相也是一种准晶近似晶体相,其结构构架可能由（Ｆｅ＋Ｖ）和（Ａｌ＋Ｓ     

气相蒸发Ti-Fe系合金纳米粉末相生成规律及尺寸效应研究

采用电弧加热蒸发法制备出粉末粒度在5nm～30nm的Ti-Fe系合金纳米粉末，研究了纳米粉末的相生成规律以及混合物粉末的尺寸效应。实验结果表明，纳米粉末中化合物相的生成规律与Ti-Fe合金平衡相图的不同。蒸发Fe含量大于73％（质量分数，下同）的母合金时易得到FCC相和Fe2Ti相，而蒸发Ti含量大于47％的母合金易得到以FCC相和FeTi相为主的粉末，且所有粉末中FCC相含量最多。当母合金中Fe含量为53％时，粉末中FeTi相的相对含量是所有粉末中最高的。只有在蒸发Ti含量为90％的母合盒所得的粉末中检测到了少量Ti单质相。FCC相的d（111）晶面间距随母合金中Ti含量的增加而增加，说明FCC为固溶体相。DSC结果表明，纳米粉末的平均熔点明显低于粉末中各个合金相在平衡状态下的熔点。     

Microstructures and Mechanical Properties of Mg-2Y-xZn (x=1, 2, 3 at%) Alloys

研究了Mg-2Y-xZn(x=1,2,3 at%)合金在铸态、退火态和挤压态的显微组织与力学性能。结果表明:随着合金中Zn含量的增加,合金显微组织中第二相依次为18R-LPSO相、(LPSO+W)混合物和W相。在退火过程中,层片状的14H-LPSO结构析出并沿块状18R-LPSO结构向基体中生长,W相由铸态时弯曲的条纹状转变为颗粒状。经过挤压变形后,LPSO结构和W相均沿挤压方向排列,合金性能得到大幅度提高,其中Mg-2Y-1Zn合金具有最好的室温力学性能,抗拉强度为320 MPa,延伸率达到11.2%。     

Mg-4Zn-2Al-0.5Ca合金时效沉淀过程的相演变

利用高分辨透射电镜和扫描电镜分析了Mg-4Zn-2Al-0.5Ca合金时效沉淀过程中的相演变。结果表明:试验合金的时效硬化曲线呈现典型的时效硬化特征。试验合金在160℃时效达到峰值硬度时其沉淀相有:平行于(0001)Mg的圆盘状沉淀相、(梳齿状)块状沉淀相以及大量的亚稳过渡相。随时效时间的延长,生成长条状相,但基体中依然存在很多后析出的细小的弥散分布的粒状沉淀相。120℃×230 h时效处理后的微观组织中存在着蜂窝状组织,宽度为3～4 nm的长条状沉淀相,直径为5～7 nm的球状沉淀相;这些沉淀相的存在大大提高了合金的硬度。     

Investigation of the titanium–indium system

The phase diagram of the Ti–In system was determined using DTA, XRD and EDX analyses. The existence of the phases Ti₂In₅ [Mn₂Hg₅ type structure, space group P4/mbm, a=0.99995(3), c=0.29960(2) nm] and Ti₃In [Ni₃Sn type structure, space group P6₃/mmc, a=0.5978(1), c=0.4812(1) nm] was confirmed. The phase previously labeled Ti₃In₂ was found to exist in a narrow homogeneity region near Ti₅₆In₄₄. Rietveld refinement of the XRD powder pattern yielded solutions compatible with a Cu₃Au-type or a BiIn-type crystal structure, but not with a CuAu-type crystal structure. Furthermore, at 38.5 at.% In, a new phase was observed having a γ-brass related crystal structure [Ti₈In₅, space group , a=0.99578(6) nm]. The intermetallic phases were formed by a cascade of peritectic reactions ending in a eutectic at >99 at.% indium between Ti₂In₅ and (In) at 0.4 K below the melting temperature of pure indium.     

AZ91D镁合金化学镀Ni-P及Ni-W-P镀层的结构与耐蚀性

在AZ91D镁合金上直接化学镀Ni-P和Ni-W-P镀层,并利用扫描电子显微镜、X射线衍射仪及电化学工作站研究后续热处理对化学镀层组织形貌、相组成及其耐蚀性的影响。结果表明,制备的Ni-P镀层为非晶态,而Ni-W-P镀层为纳米晶结构,两者在3.5%NaCl水溶液中的耐蚀性相当。热处理可以明显提高Ni-W-P镀层的耐蚀能力,但却稍微弱化Ni-P镀层的耐蚀能力,热处理后的Ni-W-P层自腐蚀电位相对于未处理的化学镀Ni-W-P或Ni-P层提高了约150 mV。     

MICROSTRUCTURE STUDY OF CONSTITUENT PHASES IN 2024 SERIES Al ALLOYS

X-ray microanalysis,convergent beam electron diffraction(CBD)and selected area electrondiffraction(SAD)studies on the structures and compositions of the constituent phases in2024 series Al alloys have been conducted.Partial substitution of alloying elements is found tooccur in all the constituent phases,which cause small deviations from the stoichiometric com-positions reported in these ternary compounds.The dominant phase is α-Al_(12)(FeMn)_3Si whichhas a body center cubic crystal structure with the Im■ space group and a=1.25 nm.The nextdominant phase is Cu_2FeAl_7 which has a primitive tetragonal crystal structure with theP4/mnc space group and a=0.6336 nm,c=1.487 nm.The minor phase is α'-Al_(12)Fe_3Si hav-ing α primitive cubic crystal structure with the Pm■ space group and α=1.27 nm.     

Fe79Zr9B12和Fe76Zr9B15合金的晶化行为和磁性能

采用单辊快淬法制备Fe79Zr9B12和Fe76Zr9B15非晶合金薄带,并对两合金进行不同温度下热处理。利用差热分析仪(DTA)、X射线衍射仪(XRD)和振动样品磁强计(VSM)研究Fe79Zr9B12合金和Fe76Zr9B15合金的晶化行为和磁性能。结果表明,Fe79Zr9B12合金和Fe76Zr9B15合金的晶化激活能分别为404.42 kJ/mol和370.75 kJ/mol。晶化初期,有α-Mn型相和α-Fe相从Fe79Zr9B12非晶合金基体中析出,Fe23B6型相和α-Fe相从Fe76Zr9B15非晶合金基体中析出。α-Mn型相和Fe23B6型相均为亚稳相,进一步高温热处理后,α-Mn型相转变为α-Fe相,Fe23B6型相转变为α-Fe相、Fe2B相和Fe3B相。Fe79Zr9B12合金的矫顽力(Hc)在600℃退火后突然增大,继续高温退火,Hc下降;Fe76Zr9B15合金的Hc随着退火温度的升高持续增大。两种合金矫顽力随退火温度的变化与退火后合金的微观结构密切相关。