Al-Ni-Fe系铸态合金中的准晶相

系统研究了Al72.5Fe14.5Ni13和Al71Fe5Ni24铸态合金的相组成，发现其中分别存在D—Al72．6Fel4．6Nil2．8和D'—Al70．5Fe10Nil9．5两种十次准晶，它们各自与AlFe和AlNi二元十次准晶相关．实验结果与三元准晶相图的电子浓度特征吻合，说明三元准晶相图的电子浓度特征对确定三元准晶的理想成分和探索准晶新成分有一定的指导作用．     

Ti38Zr45Ni17准晶合金的储氢性能及其V合金化

研究了三元Ti38Zr45Ni17准晶合金及其V合金化后的四元合金(Ti0.38Zr0.45Ni0.17)100-xVx(x=5%、10%、30%、40%、60%(原子分数))的吸放氢性能.准晶成分设计思想源自于团簇线方法,即在Ti-Zr-Ni三元合金体系中利用两条团簇线的交点确定最佳准晶成分Ti38Zr45Ni17.利用铜模吸铸快冷工艺制备直径为3mm的合金棒.吸放氢测试结果表明,Ti38Zr45Ni17准晶在303K首次吸氢量为0.9%(质量分数),在573K时合金首次吸氢量可达2.38%(质量分数),合金吸氢过程快速完成,并放出大量的热,可将吸氢前的粉末样品烧结成块体凝聚物.吸氢后准晶结构消失,完全转化为氢化物结构.添加5%～30%(原子分数)的V进行合金化时可提高合金在573K下的首次吸氢量,最大为2.96%(质量分数);具有固溶体结构的(Ti0.38Zr0.45Ni0.17)40V60合金在室温下首次吸氢量为3.2%(质量分数).由于准晶及其V合金化的合金在吸放氢之后均形成了稳定的氢化物,导致其放氢非常困难.     

Ti对Zr-Al-Ni非晶合金玻璃形成能力和热稳定性的影响

四元非晶形成体系中，具有相对较大玻璃形成能力和热稳定性的合金成分点位于该四元成分图的等电子浓度面和等原子尺寸面的交线上。本文以Zr60Al20Ni20非晶合金的电子浓度和原子尺寸为基础，根据等电子浓度和等原子尺寸判据，添加Ti元素，设计了一系列Zr-Ti-Al-Ni四元合金，分析了Ti元素对Zr-Al-Ni非晶合金玻璃形成能力和热稳定性的影响。研究发现，在较低的Ti含量情况下，样品主要由非晶相组成，Ti的加入降低了合金的热稳定性和玻璃形成能力。     

准晶材料的形成机制,性能及应用前景

本文结合作者的工作综述了准晶的形成机制、性能特点及潜在的应用等几方面的国际最新进展这些进展都与电子结构有关，准晶是一种极特殊的电子合金相（Ｈｕｍｅ－Ｒｏｔｈｅｒｙ相），其伪Ｂｒｉｌｌｏｕｉｎ区为接近Ｆｅｒｍｉ球面的多面体，因而产生强烈的相互作用这种特性影响到准晶的各种行为，如形成过程、与类似相的关系等等．以硬度高、不粘和弱导电导热为代表的性能指标为准晶的应用开辟了广阔前景     

电沉积制备Fe-Cr-Ni泡沫合金工艺研究

以聚氨酯泡沫为基体,通过化学镀镍、电沉积Fe-Cr合金和烧结处理等工艺制备了Fe-Cr-Ni三元泡沫合金,研究了其制备工艺条件,尤其是电流密度、Cr3 浓度与Fe2 浓度的比值和镀液pH值等对镀层质量和三元泡沫合金中铬元素含量的影响,得到在聚氨酯泡沫上电沉积Fe-Cr合金的最佳工艺为:pH=2～3,c(Cr3 )/c(Fe2 )=10～12,电流密度15～22 A/dm2,搅拌.用X射线荧光探针(XRF)对用最佳工艺下制备的三元泡沫合金的化学成分进行了测试,测得其中Cr在18%～20%之间,Ni在8%～10%之间,Fe在70%～74%之间,其成分与18-8不锈钢很接近.     

氮杂碳包Fe、Co、Ni材料的合成及介电特性

采用交流电弧法,在氮气氛下合成了氮杂碳包金属Fe、Co、Ni纳米晶.采用热重分析(TG)法测量了合成材料中Fe、Co、Ni等金属的含量.借助于透射电子显微镜(TEM)、粉末衍射法(XRD)、X光电子能谱法(XPS)等分析手段进行了合成材料的形貌观察和结构表征.采用反射-传输网络参数法在HP8510B矢量网络分析仪上进行了材料复介电常数测量.结果表明氮杂碳包金属Fe、Co、Ni纳米晶在8.2～12.4GHz频率范围内具有复介电特性,其损耗角正切tgδε=ε"/ε′平均值分别达到0.9,0.31和0.30,显示出氮杂碳包金属Fe、Co、Ni纳米晶对微波具有较好的介电损耗特性.     

Al—Fe—V—Si（Nd）合金纳米晶粉末的制备及相转变的研究

利用机械合金化方法制备Al-Fe-V-Si(Nd)合金粉末,球磨状态下得到合金粉末由铝固溶体组成,经适当的热处理后,得到α-A112(Fe,V)2Si粒子弥散分布的合金末,加入稀土后,合金粉末的组织得到细化,并出现非晶化的趋势。利用DNMA方法可以直接得到具有α－Al13(Fe,V)3Si粒子弥散分布的合金粉末,并观察到α－Al13(Fe,V)3Si 转变为准晶的现象,从而证实了准晶相与αAl13(Fe,V)3Si之间的强烈关联性。     

Al20Si20Mn20Fe20Ga20中近等原子比高熵十次准晶

准晶是结构复杂相,通常以一种合金元素为主要成分.高熵合金含有多种主要合金元素,其晶体结构却往往是比较简单的立方相.作为结构和成分均复杂的高熵准晶却难以在实验上制备和理论上预测,研究人员对其结构特点也知之甚少.因而高熵准晶的制备和结构特性引起了人们的广泛关注.我们报道了一种在Al20Si20Mn20Fe20Ga20甩带样...     

单轴-平面W型复合锶铁氧体的制备及其吸波特性研究

用草酸盐共沉淀和微量掺杂法研制六角晶系W型Ni,Zn,Co,Al多元复合锶铁氧体，通过调节Ni2W同Co2W的摩尔比例，可使该种铁氧体易磁化方向从C单轴型向垂于C轴的平面型转化，控制置换锶铁氧体中部分Fe3 的微量掺杂Al3 ，可以调整4πMs值，提高磁晶各向异性场，测试分析了5种不同含Co量的W型复合锶铁氧体粉料涂层的吸波特性，发现其自然共振吸收峰随Co含量增加向低频方向偏移，最高吸收峰可达32．8dB，是适用于电子隐形技术的高品位的微波吸收剂。     

Al63Cu25Fe12准晶粉末的制备及物相分析

采用铸态Al63Cu25Fe12准晶材料进行球磨和高压惰性气体（N2）雾化水冷快速凝固两种方式，制备了各种粒度的Al63Cu25Fe12准晶粉末，经筛分后为－40～80目、－80～200目及－200目的粉末。对两种工艺下获得的粉末做了粒度组成分析和X射线衍射分析，发现雾化法制得的粉末中相的组成远比球磨粉末的简单，而且随着粉末粒度细化，雾化粉末中准晶相的相对含量增加，但增加的幅度降低，最后在变化曲线上趋于平缓。差示扫描量热法（DSC）分析结果表明，雾化粉末中不存在铸态材料中出现的先析出相λ相（Al13Fe4)。     

Zr-Al-Ni-Co块体非晶合金的成分设计

选择Zr-Al-Ni-Co合金系为研究体系,以等电子浓度和等原子尺寸为判据设计8种合金,采用吸铸法制备了直径为3 mm的合金棒,XRD结果表明了在等电子浓度面和等原子尺寸面交线上存在着一个较大范围的块体非晶合金形成区域.能够形成块体非晶合金的7种合金,具有相近的约化玻璃转变温度Trg值,最大达到0.589;它们的玻璃转变温度Tg值略有差异,且从三元Zr-Al-Co一侧至三元Zr-Al-Ni一侧,其值逐渐减小,最高Tg=713 K.将Zr-Al-Ni-Co合金系与用相同方法设计的块体非晶合金Zr-Al-Ni-Cu和Zr-Al-Ni-Fe体系进行了比较.     

Density and viscosity of ternary Cr–Fe–Ni liquid alloys

The density and viscosity of ternary Cr–Fe–Ni liquid alloys have been investigated over a wide temperature range. The density was measured using electromagnetic levitation as a container-less technique, while viscosity was measured by means of a high-temperature oscillating cup viscometer. Although, the concentration dependence of density shows the influence of the second order (binary) interaction parameter in excess volume, the influence of a third order (ternary) interaction parameter in excess volume can be neglected. The temperature dependences of the viscosities are well described by the Arrhenius law. The viscosity increases monotonically as Fe or Cr concentration increases. For constant temperature, the viscosity as a function of iron molar faction can be described by a thermodynamic model using the enthalpy of mixing as input parameter.     

Structure and tribological property of B2-based approximants

The present paper is concerned with a special group of approximants with B2 superstructures. In the first part, recent work on structural features of the B2 superstructure approximants is summarized. Experimental results obtained in Al-Cu-Mn and Al-Cu systems are presented, where a series of B2-based approximants are observed. These phases all have similar valence electron concentrations, in full support of thee/a-constant definition of approximants. Special emphasis is laid on the chemical twinning modes of the B2 basic structure in relation to the Al-Cu approximants. It is revealed that the B2 twinning mode responsible for the formation of local pentagonal atomic arrangements is of 180°/[111] type. This is also the origin of 5-fold twinning of the B2 phase on quasicrystal surfaces. Crystallographic features of phases B2, τ2, τ3,γ, and other newly discovered phases are also discussed. In all these phases, local pentagonal configurations are revealed. In the second part, dry tribological properties of some AlCuFe samples containing the B2-type phases are presented. The results indicated that the B2 phase having their valence ratio near that of the quasicrystal possesses low friction coefficient under various loads, comparable with the annealed quasicrystalline ingot. Such a result indicates that the B2-type phase withe/a near that of quasicrystal is indeed an approximant, which is in full support of the valence electron criterion for approximants.     

Electronic Structure of New Superconducting Perovskite MgCNi3

The electronic structures of new superconducting perovskite MgCNi3 and related compounds MgCNi2T (T=Co, Fe, and Cu) have been studied using MS-Xa method. In MgCNi3, the main peak of density of states is located below the Fermi level and dominated by Ni d. From the results of total energy calculations, it was found that the number of Ni valence electron decreases faster for the Fe-doped case than that for the Co-doped case. The valence state of Ni changes from +1.43 in MgCNi2Co to +3.02 in MgCNi2Fe. It was confirmed that Co and Fe dopants in MgCNi3 behave as a source of d-band holes and the suppression of superconductivity occurs faster for the Fe-doped case than that for the Co-doped case. In order to explain the fact that Co and Fe dopants in MgCNi3 behave as a source of d-band holes rather than magnetic scattering centers that quench superconductivity, we have also investigated the effects of electron (Cu) doping on the superconductivity and found that both electron (Cu) doping and hole (Co, Fe) dopin     

Environmental Embrittlement in A_3B-type Intermetallic Alloys

Environmental embrittlement in A3B-type intermetallics based on Ni3Al and Fe3Al has been studied in this paper. For the Ni3Al doped with 120 wt ppm B and Ni,(Al,Cr.Zr) doped with 80 wt ppm B,their elongation and ultimate tensile strength decreased in the sequence:of vacuum > air >hydrogen. while for Ni,(Al,Mn) doped with 400 wt ppm B no envifonmental degradation was ob served, although a -Ni3(Al,Mn) alloy without B showed a decrease in ductility when tested in air in stead of oxygen. It is supposed that boron and hydrogen compete for the occupation of interstitial sites near grain boundaries. If boron content is sufficiently low, hydrogen embrittlement occurs ;however, if its content is sufficiently high. boron addition is capable of eliminating envjronmental ef fect in Ni3Al-based alloysi As to the micromechanism of hydrogen embrittlement in Ni3Al+B. S EM in situ observations showed that both grain boundary decohesion and a high stress concentration con tributed to hydrogen-assisted jntergranu lar cracking in this alloy. For the Fe3Al and Fe3 (Al.Cr) alloys.their mechanical properties depended strongly on grain size / grain shape and testing environment. A strain rate effect on ductiIity and fracture strength was also observed in the Fe3Al and Fe,(Al,Cr)+B aIloys. Preoxidation increased the ductility of the Fe,(Al,Cr)+B alloy. All these results can be rationalized from a hypothesis that surface reaction is the controlling process in embrittling Fe3Al-based alloys.     

Study on TiAl2-based ternary (Fe or Ni) titanium aluminides

Several ternary alloys were designed to help understand the type of substitution and the nature of transformation in L1₂-type ternary (Fe or Ni) titanium aluminides. X-ray powder diffraction analysis, scanning electron microscopy and microhardness measurements were used to delineate the phases present in arc-melted alloys that were annealed at 1300 K for 10 days. The results of this study show that, in L1₂ type ternary (Fe, Ni) titanium aluminides, Fe or Ni substitutes for Ti, and these materials are TiAl₂-based, contrary to previous assumptions.     

铝基准晶的研究进展

概述了铝基准晶态合金的形成机理,其形成存在着相似性原则,具有电子浓度特征.分析了铝基准晶合金的组织与相变特征,铝基准晶的生成通常为包晶、包析反应,其长大速度较慢.综述了铝基准晶合金的性能,铝基准晶具有高的硬度、高的弹性模量及高的强度,室温下塑性小,表现为脆性;铝基准晶具有优良的抗腐蚀性能;铝基准晶具有低摩擦因数和抗摩损的特征.对铝基非晶合金的应用进行了评述.     

Zr基大块非晶合金成分的等电子浓度和等原子尺寸判据

制备了6种合金Zr65.5Al5.6Ni6.5Cu22.4,Zr65.3Al6.5Ni8.2Cu20,Zr65Al7.5Ni10Cu7.5,Zr64.8Al8.3Ni11.4Cu5.5,Zr64.5Al9.2Ni13.2Cu13.1和Zr63.8Al11.4Ni17.2Cu7.6,共晶成分位于合金Zr64.5Al9.2Ni13.2Cu13.1和合金Zr63.8Al11.4Ni17.2Cu7.6的成分之间，这6种合金均显示了非晶相的形成和较宽的过冷液相区范围△Tx值，以及较大的约化玻璃转变温度Trg值，除合金Zr63.8Al11.4Ni17.2Cu7.6的△Tx值为87K外，其余5种成分合金的△Tx值均在97K以上，最宽的达105K，表明这6种合金是一个具有大玻璃形成能力和高热稳定性的非晶合金系列，合金Zr63.8Al11.4Ni17.2Cu7.6是6种合金中玻璃表成能力和热稳定性最高的，其Tg，Tx和Trg值最高，Inoue非晶合金Zr65Al7.5Ni10Cu17.5并不是最佳非晶成分，提出以等电子浓度和等原子尺寸规律作为设计大块非晶合金成分的判据。