快淬NdFeB永磁合金的晶化行为

采用动态差示扫描量热法（ＤＳＣ）和Ｘ射线衍射法（ＸＲＤ）研究了淬ＮｄＦｅＢ合金的晶化行为。非晶态Ｎｄｓ、５Ｆｅ８６Ｂ５．５合晶化由三个过程组成,各转变有效晶化激活能分别为４．８ｅＶ、１５。２ｅＶ和５．４ｅＶ。非晶态Ｎｄ７．５Ｄｙ１Ｆｅ８５Ｂ４５Ｃａ２合金直接由非晶态转变为α－Ｆｅ和Ｎｄ２Ｆｅ１４Ｂ相,有效晶化激活能为５．８ｅＶ。     

轧制对Zr（60）Al（15）Ni（25）块体非晶合金晶化动力学的影响

通过线性DSC实验研究了轧制对Zr60Al15Ni25大块非晶合金晶化动力学的影响。实验结果表明,Zr60Al15Ni25非晶合金在轧制塑性变形过程中,随着变形量的增加,热稳定性降低。Zr60Al15Ni25块体非晶合金轧制后原子组态的变化主要影响晶化的形核阶段,变形量较低时（20%）合金原子组态向无序方向发展,导致晶化速率变慢,晶化变得比较困难。随着轧制的进一步增加,合金原子的无序性降低,晶化速率又逐渐提高,从而使其在随后加热过程中的晶化变得比较容易。     

Vogel—Fulcher定律与玻璃转变温度的关系

文章通过测定Ｉｎ、Ｚｎ、Ｓｎ、ｐｂ等元素随加热速度变化在不同坩埚和不同重量条件下其熔点变化的规律,校正了加热速度对差示扫描量热仪显示的影响。根据对仪器温度校正的结果,测量了Ｎｉ３３Ｚｒ６７、Ｚｒ６５Ａｌ７．５Ｎｉ１０Ｃｕ１５Ｃｏ２．５、Ｐｔ６９．０Ｎｉ９．６Ｐ２１．４、聚醚砜（ＰＥＳ）和聚苯乙烯（ＰＳ）等材料的玻璃转变的动力学特征。结果表明玻璃转变温度的增加与加热速度对数的增加成正比,而这种关系并     

金属玻璃晶化过程的相形成研究

本文采用差示扫描量热仪（DSC），X射线衍射仪（XRD）及透射电镜（TEM）系统地研究了金属玻璃Ni68B21Si11分别在等温退火和连续加热过程中的晶化动力学与相形成顺序，Ni68B21Si11非晶合金具有较高的热稳定性，其DSC曲曲因升温速率不同而呈现两个或三个晶化放热峰，首次发现该金属玻璃在向稳定晶体转变之前，形成一种f.c.c.结构的亚稳相。     

Zr_(65)Al_(7.5)Ni_(10)Cu_(15)Co_(2.5)合金的比热和热力学函数

采用差示扫描量热仪和差热分析仪测定了Ｚｒ６５Ａｌ７．５Ｎｉ１０Ｃｕ１５Ｃｏ２．５非晶合金的结晶温度和结晶焓、晶态的熔化温度和熔化焓、非晶态和晶态及液态的比热等热力学数据。在此基础上通过设晶态２９８Ｋ的自由焓为零，得到了晶态、非晶态和液态的热力学函数，据此研究了玻璃转变和真实玻璃转变温度，分析了理想玻璃转变温度、真实玻璃转变温度和实际测量的玻璃转变温度的关系。     

Zr65Al7.5Ni10Cu15Co2.5合金的比热和热力学函数

采用差示扫描量热仪和差热分析测定了Ｚｒ６５Ａｌ７．５Ｎｉ１０Ｃ１５Ｃｏ２．５非晶合金的结晶温度和结晶焓，晶态和熔化温度和熔化焓，非晶态和晶态及液态的经热等热力学数据，在此基础通过设昌态２９８Ｋ的自由焓为零，得到了晶态，非晶态和液态的热力学函数，据此研究了玻璃转变和真实玻璃转为温度，分析了理想玻璃转为温度，真实玻璃转为温度和实际测量的玻璃转为温度的关系。     

具有表面扩散反应的非晶FMSB晶化热力学机制研究

研究了在大气压力为３×１０３～５×１０３ＭＰａ、温度为７８３～９０３Ｋ时，表面具有与Ａｌ发生扩散反应的非晶（Ｆｅ０．９９，Ｍｏ０．０１）７８Ｓｉ９Ｂ１３即ＦＭＳＢ合金的晶化过程，给出了α－Ｆｅ（Ａｌ）和α－Ｆｅ（Ｍｏ，Ｓｉ）的Ｇｉｂｂｓ′自由能随压力的变化及非晶ＦＭＳＢ的晶化机制     

Cu—Zr及Cu—Ta机械合金化过程中的非晶转变

本文系统地研究了Ｃｕ基合金体系机械驱动下的非晶转变。研究结果表明具有负混合热焓的Ｃｕ－Ｚｒ和具有正混合热焓的Ｃｕ－Ｔａ体系的混合粉末以及没有化学驱动的金属间化合物Ｃｕ１０Ｚｒ７都能通过高能球磨方法实现非晶化转变。球磨过程中的机械储能是非晶化的主要驱动力。原子径向分布函数和核磁共振的结果表明机械合金化是一个原子尺度合金化过程，形成的非晶在结构上与急冷技术得到的非晶合金是相同是。     

两种稀土基大块非晶合金非等温晶化行为的研究

以不同加热速率下的DSC曲线数据为基础,利用Kissinger及Deloy激活能计算方法研究了Mm55Al25Cu10Ni5Co5与La55Al25Cu10Ni5Co5大块非晶合金的非等温晶化动力学。结果表明:两非晶合金的玻璃转变温度(Tg)、晶化初始温度(Tx)和晶化峰值温度(Tp)都随着加热速率的增加而增加,具有明显的动力学效应;阶段激活能随晶化体积分数的增加,先迅速增加,达到最大值后缓慢下降,为典型的形核及长大机制且形核瞬间完成,晶化以生长为主。Mm55Al25Cu10Ni5Co5非晶合金的玻璃转变激活能、形核激活能和长大激活能以及晶化初期激活能和最大激活能都相应大于La55Al25Cu10Ni5Co5表明前者比后者具有更高的热稳定性。     

Fe73.5Si13.5B9Cu1Nb3-xMox（x=1,2,3）非晶合金的晶化动力学研究

采用单辊熔体快淬法在大气环境中制备Fe73.5Si13.5B9Cu1Nb3-xMox（x=1,2,3）非晶合金薄带,利用差示扫描量热分析和X射线衍射分析进行非晶合金的晶化动力学研究,计算出Fe73.5Si13.5B9Cu1Nb3-xMox（x=1,2,3）非晶薄带的晶化激活能分别为349、262、332 kJ/mol,其Avrami指数分别为1.95、2.14和2.00。结果表明,随着升温速率的提高,Fe73.5Si13.5B9Cu1Nb3-xMox（x=1,2,3）非晶薄带的起始晶化温度和晶化峰值温度相应升高;以Mo部分替代Nb降低了非晶合金的晶化激活能;-αFe（Si）软磁相具有扩散控制的低维形核和生长的晶化机制,且形核率逐渐减小。     

Nd_(60)Al_(10)Ni_(10)Cu_(20)大块金属非晶的玻璃转变和晶化特性研究

用铜模吸铸法制得了一种直径为5 mm、成分为Nd60Al10Ni10Cu20的大块非晶合金.与富Fe类Nd基非晶不同的是,这种新型的Nd基大块非晶具有明显的玻璃转变过程和稳定的过冷液相区.磁性测试表明,在室温下表现为顺磁性.热分析实验发现,随着升温速率的增大,样品的过冷液相区变宽,并且玻璃转变温度和晶化温度有明显的向高温方向移动的趋势.研究了该大块非晶的玻璃转变动力学和晶化动力学,并给出了Kauzmann温度Tk,Vogel-Fulchers-Tamman温度T0g以及脆性系数m等重要参数.     

Effects of Heating Rate on the Process Parameters of Superplastic Forming for Zr_(55)Cu_(30)Al_(10)Ni_5

We investigated the effects of heating rate on the process parameters of superplastic forming for Zr55Cu30Al10Ni5 by differential scanning calorimetry. The continuous heating and isothermal annealing analyses suggested that the temperatures of glass transition and onset crystallization are heating rate-dependent in the supercooled liquid region. Then, the time-temperature-transformation diagram under different heating rates indicates that increasing the heating rate can lead to an increase of the incubation time at the same anneal temperature in the supercooled liquid region. Based on the Arrhenius relationship, we discovered that the incubation time increases by 1.08-1.11 times with double increase of the heating rate at the same anneal temperature, and then verified it by the data of literatures and the experimental results. The obtained curve of the max available incubation time reveals that the incubation time at a certain anneal temperature in the supercooled liquid region is not infinite, and will increase with increasing heating rate until this temperature shifts out of the supercooled liquid region because of exceeding critical heating rate. It is concluded that heating rate must be an important processing parameter of superplastic forming for Zr55Cu30Al10Ni5.     

Effects of heating rate on the process parameters of superplastic forming for Zr<Subscript>55</Subscript>Cu<Subscript>30</Subscript>Al<Subscript>10</Subscript>Ni<Subscript>5</Subscript>

We investigated the effects of heating rate on the process parameters of superplastic forming for Zr₅₅Cu₃₀Al₁₀Ni₅₅ by differential scanning calorimetry. The continuous heating and isothermal annealing analyses suggested that the temperatures of glass transition and onset crystallization are heating rate-dependent in the supercooled liquid region. Then, the time-temperature-transformation diagram under different heating rates indicates that increasing the heating rate can lead to an increase of the incubation time at the same anneal temperature in the supercooled liquid region. Based on the Arrhenius relationship, we discovered that the incubation time increases by 1.08–1.11 times with double increase of the heating rate at the same anneal temperature, and then verified it by the data of literatures and the experimental results. The obtained curve of the max available incubation time reveals that the incubation time at a certain anneal temperature in the supercooled liquid region is not infinite, and will increase with increasing heating rate until this temperature shifts out of the supercooled liquid region because of exceeding critical heating rate. It is concluded that heating rate must be an important processing parameter of superplastic forming for Zr₅₅Cu₃₀Al₁₀Ni₅.     

金属玻璃P1峰弛豫激活能的一种计算新方法

提出了金属玻璃P1峰弛豫激活能的一种计算方法 .计算金属玻璃P1峰激活能的常用方法是由不同频率下升温测得的不同内耗峰的温频关系来求得 .然而 ,自由衰减法有限的变频范围 ,以及由于受晶化的影响 ,使两次升温测量时样品的初始状态不易重复 ;用强迫振动法测量时 ,同步变频条件限制了升温速率 ,造成金属玻璃的晶化过程严重影响了测量结果 .该方法仅用自由衰减法一次升温测得的内耗峰及损耗模量峰的温频关系 ,便可以计算出金属玻璃P1峰的弛激活能     

Low-frequency Internal Friction Behaviour of Zr_(55)Al_(10)Ni_5Cu_(30) Metallic Glass with Different Quenching Temperatures

The correlation between the internal friction behaviour of Zr_(55) Al_(10) Ni_5 Cu_(30) BMG samples and their quenching temperatures was investigated. It was found that, below the glass transition temperature, the activation energy decreased with increasing quenching temperature, but in the surpercooled liquid region the activation energy tended to be enhanced with a further increase in the quenching temperature. Besides, there were both anelastic and viscoelastic relaxation for the amorphous alloys. The anelastic behaviour would change into viscoelastic relaxation easily for the samples prepared at higher temperature.     

Crystallization kinetics of calcium aluminate glasses studied by non-isothermal techniques

The crystallization kinetics of 38.0CaO-38.0Al₂O₃-10.5BaO-6.5MgO-6.0Y₂O₃-1.0(Na₂O+K₂O) (wt%) glass was studied by differential scanning calorimeter (DSC) and X-ray diffraction (XRD) techniques. The results showed that DSC curves of calcium aluminate glass have a single glass transition temperature followed by one crystallization peak for the heating rates β = 5 K/min and two crystallization temperatures T _p1 and T _p2 for β ≥ 10 K/min. The activation energies of crystallization obtained from the Gao-Wang model of the first exothermal peak and the second exothermal peak of calcium aluminate glass are 340 and 662 kJ/mol, respectively. The Avrami exponents of the both crystallization peaks are approximately 2, indicating the twodimensional crystalline growth during its transformation from amorphous to crystalline. Ca₁₂Al₁₄O₃₃, Ca₃Al₂O₆ and unknown crystalline phases firstly appear when calcium aluminate glass is heat-treated. With the extending of heat-treatment duration, BaAl₂O₄ phase comes out.     

Influence of flux treatment on the glass forming ability of Pd-Si binary alloys

Pd₈₁Si₁₉ amorphous alloys were prepared by combination methods of melt spinning and B₂O₃ flux treatment. A comparison between the ribbons prepared from the fluxed ingots and the non-fluxed ones has been carried out. The result reveals that after fluxing treatment the glass transition temperature of the as-prepared glassy ribbons is reduced while the initial crystallization temperature is enhanced. It results in that the supercooled liquid region (defined as the difference between the initial crystallization temperature and the glass transition temperature) of the glassy alloy treated with fluxing technology has been increased from 31 to 42 K. This shows that fluxing technique can enhance the glass forming ability (GFA) of the binary alloy and improve the thermal stability of supercooled liquid of the glassy alloy.     

Glass formation of ternary Sm-based Sm-Al-Co bulk metallic glasses

Ternary Sm-based Sm-Al-Co alloys at specific compositions designed using an e/a- and cluster-related criteria exhibit high glass forming abilities and form bulk glassy rods of 3 mm in diameter by a copper mold suction-casting method. Four composi- tions of bulk metallic glasses (BMGs) are Sm50Al25Co25, Sm52Al24Co24, Sm54Al23Co23 and Sm56Al22Co22, which all satisfy a constant conduction electron concentration of 1.5. Among them, the BMG exhibiting the largest reduced glass transition temperature (Trg) is Sm50Al25Co25, which reaches 0.648. The glass transition temperature Tg and the onset crystallization temperature Tx of this alloy are respectively 579 and 640 K at a heating rate of 20 K/min.