纳米金属间化合物NiAl的机械合金化合成及性能

利用机械合金化和高温热压工艺制备ＮｉＡｌ纳米晶体材料,并研究了材料的微观组织和力学性能。结果表明,ＮｉＡｌ的反应生成归结于机械碰撞诱发的爆炸反应机制,采用高温热压工艺可制备接近完全致密的纳米晶ＮｉＡｌ块体材料。ＮｉＡｌ纳米晶体材料的室温强度和塑性都高于铸态ＮｉＡｌ,纳米晶ＮｉＡｌ的高温强度依赖于应变速率,变形受扩散机制控制。     

热压NiAl纳米晶块体材料的HREM观察及EDS分析

利用高分辨电镜（ＨＲＥＭ）及场发射电镜纳米尺度成分分析技术（ＥＤＳ分析）研究了机械合金化和真空热压技术制备的纳米ＮｉＡｌ块体材料的微观结构。ＨＲＥＭ及ＥＤＳ分析结果表明在球磨过程中形成第二相粒子Ａｌ２Ｏ３分布于ＮｉＡｌ晶粒内部或边界上,分布于晶粒边界上的Ａｌ２Ｏ３对晶界起钉扎作用,有效地抑制晶粒长大;此外,观察到纳米晶粒间存在无序区,这些无序区也是抑制晶粒长大的一个因素。     

弥散质点和SiC颗粒复合强化Al基复合材料 Ⅰ．制备和微观结构

采用纯Ａｌ粉、Ｃ粉和ＳｉＣ颗粒进行机械合金化和热处理，经冷压实后直接进行热挤压，成功地制备了Ａｌ_４Ｃ_３、Ａｌ_２Ｏ_３弥散质点不和ＳｉＣ颗粒复合强化Ａｌ复会材料．金相显微镜、透射电镜和高分辨电镜观察表明，ＳｉＣ颗粒与Ａｌ基体具有较好界面结合，其在基体中分布的均匀性受基体粉末特性的影响Ａｌ_２Ｏ_３含量较低且尺寸细小，Ｘ射线衍射和透镜分析难以确定．Ａｌ_４Ｃ_３为尺寸细小（直径约０．０２μｍ，长度约０．２μｍ）的棒状单晶体，与Ａｌ基体没有固定的取向关系，界面结合良好，无中间过渡层．     

电子束辐照诱发纳米Al/Al_2O_3复合颗粒中Al非晶化的纳米束斑原位分析

在 ＨＦ－２０００场发射电镜上完成了Ａｌ／Ａｌ２Ｏ３颗粒的辐照诱发Ａｌ非晶化转变和原位观察,纳米束斑综合分析表明Ａｌ非晶化转变是一个氧化过程     

惰性气体凝聚法制备纳米NiAl合金的结构及磁特性

用Ｘ射线衍射及透射电镜研究用惰性气体凝聚法制备纳米ＮｉＡｌ合金固体的结构。结果表明，纳米ＮｉＡｌ合金晶体结构与常规ＮｉＡｌ结构一致，平均粒度为８．６ｎｍ，，具有较大的晶格畸变，长程有序度有所降低。退火实验显示，当温度低于８００Ｋ时晶粒不明显长大，具有较好的抗晶粒生长能力。     

DISPERSOID AND SiC PARTICULATE STRENGTHENED Al COMPOSITES Ⅰ.FABRICATION AND MICROSTRUCTURE

采用纯Ａｌ粉、Ｃ粉和ＳｉＣ颗粒进行机械合金化和热处理，经冷压实后直接进行热挤压，成功地制备了Ａｌ_４Ｃ_３、Ａｌ_２Ｏ_３弥散质点不和ＳｉＣ颗粒复合强化Ａｌ复会材料．金相显微镜、透射电镜和高分辨电镜观察表明，ＳｉＣ颗粒与Ａｌ基体具有较好界面结合，其在基体中分布的均匀性受基体粉末特性的影响Ａｌ_２Ｏ_３含量较低且尺寸细小，Ｘ射线衍射和透镜分析难以确定．Ａｌ_４Ｃ_３为尺寸细小（直径约０．０２μｍ，长度约０．２μｍ）的棒状单晶体，与Ａｌ基体没有固定的取向关系，界面结合良好，无中间过渡层．     

Fe3Al氢脆机理的研究

用余氏理论计算了氢对Ｆｅ３Ａｌ金属间化合物键结构、键能和电子分布的影响，分析发现，Ｆｅ３Ａｌ的氢脆是由于氢原子溶入扣引起Ｆｅ，Ａｌ原子状态变化。使晶体内晶格电子数大大减少，导致晶体局域金属性减弱，并构成具有严重各向异性的键络的结果。同时得出，氢在Ｆｅ３Ａｌ中占据间隙位置。     

纳米晶Al88Ce2Ni10铝合金的形成

通过晶化法，可以将快凝Ａｌ８８Ｃｅ２Ｎｉ１０非晶铝合金制备成纳米晶合金。纳米晶合金的组织为αＡｌ固溶体和金属间化合物Ａｌ３Ｎｉ及Ａｌ１１Ｃｅ３组成的多相纳米晶结构。在６０３～７７３Ｋ较宽退火温区内，用Ｓｃｈｅｒｅｒ公式计算各晶化相，得到αＡｌ、Ａｌ３Ｎｉ及Ａｌ１１Ｃｅ３的晶粒尺寸分别为３１～３１６、２２～２０７及１９～１６５ｎｍ。结果表明，通过控制热处理条件，可以获得不同晶粒尺寸的纳米晶合金。其中获得晶粒细小、结构均匀超细纳米晶合金的最佳退火温度为第二ＤＳＣ峰值温度附近     

P／M制备的SiCp／Al复合材料的界面结构

粉末冶金制备的ＳｉＣｐ／Ａｌ复合材料中，基体与增强体之间存在多种界面类型。除了少数的干净界面、台阶界面外，具有纳米厚度的界面微区在材料中占大多数。进一步研究发现：界面微区是铝多晶体，而且微区中存在镁元素富集，并分布着点状的ＭｇＡｌ２Ｏ４氧化物。     

AlTiB中间合金中TiAl3形态的遗传与变异

对两种ＴｉＡｌ３形态的ＡｌＴｉＢ中间合金的重熔试验表明：ＴｉＡｌ３晶体形态在１０００℃以下有明显遗传性；过热至１１００℃时ＴｉＡｌ３晶体形态发生变异，原先为块状的ＴｉＡｌ３晶体转变为针片状，原先为针片状的ＴｉＡｌ３晶体则变厚变短，有转化为块状的倾向。     

Effects of TM on stability of structure corresponding to prepeak of amorphous Al_(90)TM_5Ce_5 Alloys

1　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅａｍｏｒｐｈｏｕｓａｌｌｏｙｓｉｎＡｌ ＴＭ ＲＥｓｙｓｔｅｍｓｗｉｔｈａ ｌｕｍｉｎｕｍｃｏｎｔｅｎｔｕｐｔｏ90 %ｈａｖｅｂｅｅｎｆｏｕｎｄｔｏｈａｖｅｅｘ ｔｒａｏｒｄｉｎａｒｙｈｉｇｈｓｔｒｅｎｇｔｈｃｏｍｂｉｎｅｄｗｉ     

METASTABLE STATE TRANSFOR MATIONS OF Al_3Ti BASE ALLOYS DURING MECHANICAL MILLING AND SUBSEQUENT ANNEALING

１　ＩＮＴＲＯＤＵＣＴＩＯＮＩｔｉｓｃｏｎｓｉｄｅｒｅｄｔｈａｔｔｈｅｂｒｉｔｔｌｅＡｌ３ＴｉｉｎｔｅｒｍｅｔａｌｌｉｃｃｏｍｐｏｕｎｄｃａｎｂｅｄｕｃｔｉｌｉｚｅｄｂｙｃｈａｎｇｉｎｇｉｔｓｔｅｔｒａｇｏｎａｌＤＯ２２ｓｔｒｕｃｔｕｒｅｉｎｔｏｔｈｅｃｕｂｉｃＬ１２ｓｔｒｕｃｔｕｒｅａｎｄｃｏｎｓｉｄｅｒａｂｌｅｓｔｕｄｉｅｓｈａｖｅｂｅｅｎｃｏｎｄｕｃｔｅｄｔｏｄｅｖｅｌｏｐｔｈｅＬ１２Ａｌ３ＴｉａｌｌｏｙｓｂｙａｌｌｏｙｉｎｇｗｉｔｈＦｅ,Ｍｎ,Ｃｒ,ｅｔｃ．Ｈｏｗｅｖｅｒ,ｔｈｅｒ…     

A model of the ductile–brittle transition of partially crystallized amorphous Al–Ni–Y alloys

A model of the ductile–brittle transition of partially crystallized amorphous Al–Ni–Y alloys is proposed. The strength of the partially crystalline Al–Ni–Y alloys was found to exhibit a maximum when the size of Al particles is 10 nm. Partially crystallized Al–Ni–Y alloys were also found to be brittle when the size and the volume fraction of the Al particles exceeded the optimum values. On the assumption that the diffusivity of Y is so low that Y atoms rejected from f.c.c.-Al particles are limited near the interface region and the diffusivity of rejected Ni atoms is so high that the perfectly mixed solution is readily attained in the matrix, the reactions in three regions, Al particles, Y accumulated interface layers and amorphous matrix, were derived by balancing the quantity of each element. Al–Ni–Y alloys were assumed to become brittle when the solute content of the interface layers reached the critical value (20%). The predictions based on the Y accumulation model are in good agreement with the published data available.     

添加剂对低压烧结Zr50Al15Ni10Cu25非晶态粉末力学性能的影响

以商业纯元素粉末为原料,用机械合金化方法在低真空条件下合成了以非晶态为主的Zr50Al15Ni10Cu25粉末。研究了一定量的外界添加剂C、Si3N4和SiC对体系热稳定性和晶化行为的影响。混合粉末用手工预压成形,然后在氩气氛下进行低压烧结。利用X射线衍射（XRD）、扫描电镜（SEM）、差热分析（DSC）和电子拉伸实验机对粉末样和块状样进行了测试。结果表明,合适的外界添加剂可以提高体系的析晶活化能,增强体系的热稳定性。适量的Si3N4能促进Zr50Al15Ni10Cu25非晶粉末的低压烧结性能,即有助于提高样品的烧结致密度和样品的抗弯强度。     

Crystallization and microstructure evolution of amorphous Al85Y4Nd4Ni7 alloy

The mixture model of Al85Y4Nd4Ni7 alloy in which a partially crystallized amorphous alloy is regarded as a nanocomposite of an Al nanoparticle and a remaining amorphous matrix is presented. Its evolution in the process of crystallization has been investigated by differential scanning calorimetry (DSC), X-ray diffraction (XRD), and transmission electron microscopy (TEM). Mainly amorphous structure with α-Al nanocrystals embedded in the amorphous matrix has been revealed by melt spining the alloy. Crystallization is showed to occur in three stages: (I) crystallization of amorphous alloy and formation of A1NiY, A1NdNi and unknown crystalline phases, (2) formation of Al3Y and Al3Nd, and (3) formation of Al3Ni.     

Al_(80)Ni_6Y_8Co_4Cu_2 GLASS ALLOYS CONTAINING NANOSCALE PARTICLES BY ISOTHERMAL ANNEALING OR QUENCHING

1. IntroductionPartial nanocrystalline Al-rich glajssy alloys have attracted great attention as a newmaterial because their specific strength are much higher than that of the fully amorphousAl-rich alloys and the conventional crystalline Al-based alloy[1,2]. Kim et al.I2] and Chenet al.13] reported that the values of fracture strength are above 1000MPa for Al-rich alloyswith mixed structure of nanoscale or-Al particles embedded on the amorphous matrix afterpartial crystallization. However,…     

PREPARATION OF Ti-Al BASED NANOPHASE COMPOSITE POWDER BY MECHANICAL ALLOYING

ＰＲＥＰＡＲＡＴＩＯＮＯＦＴｉＡｌＢＡＳＥＤＮＡＮＯＰＨＡＳＥＣＯＭＰＯＳＩＴＥＰＯＷＤＥＲＢＹＭＥＣＨＡＮＩＣＡＬＡＬＬＯＹＩＮＧ①ＷｕＮｉａｎｑｉａｎｇ，ＷｕＪｉｎｍｉｎｇ，ＬｉＷｕ，ＷａｎｇＧｕａｎｇｘｉｎ，ＬｉＺｈｉｚｈａｎｇＤｅｐａｒｔｍ...     

Al91Ni7Y2纳米非晶复合材料晶化的研究

利用差示扫描量热(DSC)、透射电镜(TEM)和X射线衍射(XRD)技术,对快速凝固Al91Ni7Y2,合金条带急冷态和不同温度退火态的晶化行为及显微结构演化进行了研究。结果表明：急冷态的Al91Ni7Y2合金为部分Al粒子均匀分布在非晶基底上的复合材料。从急冷态到高温平衡态有三阶段晶化过程,对所有的晶化温度和晶化相的测量表明,DSC曲线上第一个峰的初始和峰值温度分别为240℃和267℃(在加热速率为10℃／min条件下),这一相对高的温度表明此复合材料有高的热稳定性。     

冷喷涂SiC/Al纳米复合涂层的组织结构与性能

为制备基体相晶粒细小、增强相均匀分布的SiC/Al纳米复合涂层,以Al、SiC为原料,采用高能球磨法获得SiC颗粒弥散分布的纳米晶Al基复合材料粉末,利用冷喷涂技术低温成型制备了SiC/Al纳米复合涂层,分析了SiC含量对复合涂层相结构、晶粒尺寸、微观结构、硬度及磨损性能的影响规律。结果表明：冷喷涂可实现球磨纳米晶复合粉末结构的原位移植,所制备SiC/Al纳米复合涂层组织致密,微米及亚微米级SiC弥散分布在纳米晶Al（约80 nm）基体之上;SiC颗粒对Al基体有明显强化作用,冷喷涂SiC/Al纳米复合涂层的硬度随SiC体积分数的增加而显著增加,50% SiC/Al纳米复合涂层的硬度高达515 HV_0.3,约为Al块材的13倍;冷喷涂SiC/Al纳米复合涂层的耐磨损性能随着SiC含量增加而显著提高,涂层磨损失效机制为磨粒对基体的切削犁沟变形。     

Thermal behaviors of Al-based amorphous alloys bearing nanocrystalline In particles

We successfully fabricated nanocrystalline (NC) indium (In) particles embedded in Al-based amorphous matrix. Systematic investigations indicate that thermal interaction between the NC In and the amorphous matrix significantly influences their respective thermal behaviors. The melting temperature of NC In was found to be depressed by 10–30 K, owing to the specific interfacial structure of NC In/amorphous system. The simultaneous appearance of the liquid/amorphous interface destabilizes the amorphous matrix, leading to face-centered cubic-Al precipitation at the interface of In sphere/amorphous matrix at a relatively lower temperature. This effect is attributed to the diffusion of La from the matrix to the liquid In particles.