Ni-Fe-Zr-Si-B非晶合金的形成和热稳定性研究

通过旋铸急冷工艺在真空中制备出了(Ni0.75Fe0.25)78-xZrxSi10B12(x=1、3、5、8、10)合金带材,获得了镍基非晶合金.采用XRD、DTA等测试手段分析了该工艺制备的合金非晶条带,研究了Zr对该合金体系的非晶形成能力和热稳定性的影响.X射线衍射分析表明,该合金体系皆为完全非晶.Diamond TG/DAT差热分析仪对非晶薄带的热稳定性及其相关参数Tg、Tx、Tm等的测量分析表明,该合金系中(Ni0.75Fe0.25)70Zr8Si10B12的过冷液相区温度范围ΔTx达58.62 K,约化玻璃转变温度trg约为0.666,表明该合金具有较高的非晶形成能力和热稳定性.当Zr原子分数较小(x≤8)时,Zr的添加提高Tg、Tx,并扩大过冷液相区ΔTx,使合金的非晶形成能力和热稳定性增加;Zr原子分数较大(x>8)时,Zr的添加诱导富Zr-Ni和Zr-Fe的原子团的形成,这些原子团会成为均质形核的核心,降低合金的非晶形成能力和热稳定性.     

微量组分(Cr2Ni)对Cu50Zr42Al8大块非晶玻璃形成能力的影响

在水冷铜坩埚中采用铜模吸铸法制备直径为4 mm的Cu50Zr42Al8和(Cu50Zr42Al8)100-x(Cr2Ni)x(x=0、1、2、3、4)合金圆棒.利用X射线衍射(XRD)和差分扫描量热(DSC)分别对合金的结构和非晶形成能力进行研究,结果表明,Cu50Zr42Al8和(Cu50Zr42Al8)98(Cr2Ni)2为完全非晶.(Cu50Zr42Al8)98(Cr2Ni)2具有较高的过冷液相区(ΔTx达65 K)和较大的热稳定性,且为近共晶成份,但其非晶形成能力比Cu50Zr42Al8略有降低.     

悬浮熔炼-铜模吸铸法制备Cu50Zr42Al8块状金属玻璃

采用悬浮熔炼-铜模吸铸法制备了Cu基块状金属玻璃,对直径5.0 mm的Cu50Zr42Al8三元合金圆棒利用X射线衍射(XRD)和差示扫描量热法(DSC)对合金的结构和热稳定性进行了测定.实验结果表明,该合金圆棒的组织为明显的非晶相,玻璃转变温度Tg、晶化温度Tx的值分别为730 K与778 K,过冷液相区宽度ΔT值为48 K,临界冷却速度Rc为25.5 K/s,表明该合金具有较强的玻璃形成能力,悬浮熔炼-铜模吸铸法是一种适合于制备块状金属玻璃的方法.     

Ti42．5Zr7．5Cu40Ni5Sn5块体非晶合金的形成热稳定性与力学行为

采用铜模铸造方法制备了临界尺寸达4mm的Ti42．5Zr7．5Cu40Ni5Sn5块体非晶合金．该合金的过冷液相区△Tx,约化玻璃转变温度Trg,γ判据以及δ判据分别为63．9K,0．561,0．393以及1．400,这表明该合金具有优异的玻璃形成能力．这种Ti基块体非晶合金具有高达2162MPa的压缩强度,同时还有明显的塑性．     

Al对Cu基块体非晶形成能力及热稳定性的影响

采用铜模吸铸法制备直径为5mm的Cu45Zr45.5-yTi9.5Aly(y=2,4,6,8)块体非晶合金试样,研究添加Al对合金非晶形成能力的影响.经X射线衍射(XRD)、扫描电镜(SEM)和差示扫描量热分析(DSC)做结构及热稳定性分析,结果表明,当x(Al)=6%时合金系的非晶形成能力最强,过冷液相区最宽,Δtx...     

机械合金化法制备Cu-Ti-Zr基非晶合金

采用机械合金化法成功制备Cu40Ti60-xZr(x=0,10,30,50)非晶合金.研究Cu-Ti-Zr合金粉末由晶态向非晶态转变过程中的组织结构变化,探讨非晶合金的形成机制,以及非晶合金的热稳定性和晶化产物.结果表明,非晶合金直接从初始元素得到,在反应过程中没有金属间化合物出现,非晶化过程可以由间隙扩散模型来解释.Cu40TixZry非晶粉末的DSC分析表明,随着Ti含量的降低和Zr含量的升高,非晶粉末的晶化温度Tx逐渐升高,对非晶粉末在相应的Tx温度附近退火15min后发现,Cu40Ti30Zr30合金没有析出相,Cu40Ti1Zr50析出了Zr2Cu,Cu4Ti和少量的一些未知相.     

Fe74B20Ti6和Fe70B20Y4Ti6非晶合金的热性能及非晶形成能力

采用单辊快淬法制备出Fe74B20Ti6和Fe70B20Y4Ti6合金条带,通过X射线衍射仪(XRD)和差热分析仪(DTA)来研究Fe74B20Ti6和Fe70B20Y4Ti6合金的微观结构和热性能.实验结果表明,快淬速率为30 m/s时,Fe70B20Y4Ti6合金已完全形成非晶,而Fe74B20Ti6合金大部分形成非晶,有少量晶化相;其中Fe70B20Y4Ti6合金的过冷液相区宽度ΔTx高达66 K,说明Y元素的添加可以使合金具有较大的热稳定性,较强的玻璃形成能力.     

钛基大块非晶合金的晶化研究

利用铜模冷却法成功制备直径为12mm的棒状Ti40Zr25Cu9Ni8Be18（原子百分比）大块非晶态合金,X射线衍射（XRD）实验检验样品为完全非晶态。对样品进行差示扫描量热分析（DSC）考查样品的热稳定性,结果显示：过冷液相区宽度（Tg-Tx）、玻璃转变温度（Tg）及约化玻璃转变温度（Tg/Tm）分别为53K、617K和0．65。利用原位X射线测定了非晶样品的晶化过程,结果表明首先是亚稳相析出,最后转变为稳定相。最后利用不同加热速度（5K/min,10K/min,20K/min,40K/min）下的DSC对该非晶合金进行晶化动力学分析,获得了一些有价值的动力学参数。     

Mg86.33Ni12.67Y1非晶合金的制备及其低温弛豫行为

采用单辊快速凝固技术,以4种冷却速度制备Mg86.33Ni12.67Y1非晶合金,并在Tg以下进行低温退火.利用X射线衍射(XRD)、差热分析(DTA)及扫描电镜(SEM)研究该合金的非晶形成能力、热稳定性及低温弛豫过程中的结构特征.结果表明,该非晶合金的过冷液相区宽度△Tx和约化玻璃转变温度Trg最大值分别为41.05 K和0.517 1,且随冷却速度的提高,△Tx表现出增大趋势,说明其非晶形成能力和热稳定性逐渐提高;低温退火时随退火温度逐渐升高,其非晶漫散射峰最大强度所对应的20值逐渐增大,表明原子的邻间距逐渐减小,非晶内部发生结构弛豫,导致拓扑结构不稳定性降低.     

Zr基非晶合金超塑性成形工艺研究

采用感应耦合等离子体刻蚀工艺制备了微型硅模具,基于硅模具研究了非晶合金Zr41.25Ti13.75Ni10Cu12.5Be22.5的超塑性微零件成形工艺.采用差示扫描量热仪测定了Zr41.25Ti13.75Ni10Cu12.5Be22.5的过冷液相区间为360～440℃,在过冷液相区间热压成形非晶合金微零件、机械研磨去除零件飞边和采用40%的KOH溶液腐蚀去除硅模具,得到非晶合金微型零件.自主研制了成形设备,仿真分析与实验相结合,解决了成形过程中设备的温度控制问题,比较分析了不同温度下的成形结果,实验与仿真结果符合较好.在410℃条件下成功制备出模数0.03、齿数66和厚度500μm的微型内齿轮,齿形轮廓清晰,X射线衍射仪扫描结果显示该微齿轮为非晶结构,从而验证了采用该工艺制备微型零件的可行性.     

Correlation between the glass-forming ability and activation energy of crystallization for Zr75−x Ni25Al x metallic glasses

The thermal stability and the kinetics of glass transition and crystallization for Zr_75?x Ni₂₅Al _x (x = 8–15) metallic glasses were investigated using differential scanning calorimetry (DSC) under continuous heating conditions. The apparent activation energy of glass transition rises monotonously with the Al content increasing; the activation energy of crystallization increases with Al changing from 8at% to 15at%, and then decreases with Al further up to 24at%, which exhibits a good correlation to the thermal stability and the glass-forming ability (GFA). The Zr₆₀Ni₂₅Al₁₅ metallic glass with the largest supercooled liquid region and GFA possesses the highest activation energy of crystallization. The relation between the thermal stability, GFA and activation energy of crystallization was discussed in terms of the primary precipitated phases.     

Formation and corrosion properties of Fe-based bulk metallic glasses

Bulk metallic glass (BMG) formation was explored in the Fe-B-Si-Nb alloy system though combined use of the atomic cluster line approach and the minor alloying strategy. The basic ternary compositions in the Fe-B-Si system were determined by the intersection points of two cluster lines, namely, Fe-B cluster to Si and Fe-Si cluster to B. 3at%–4at% Nb was added to the quaternary Fe-B-Si-Nb alloy. The casting experiments revealed that good glass-forming ability (GFA) occurred at the (Fe_73.4Si_8.2B_18.4)₉₆Nb₄ composition, and 3-mm diameter BMG samples were made. The glass transition temperature (T_g), crystallization temperature (T_x), and supercooled liquid region (ΔT_x=T_x-T_g) of this BMG were measured to be 866, 889, and 23 K, respectively. The BMG shows a high Vickers hardness of about Hv 1164, a Young’s modulus of 180 GPa, and a good corrosion resistance in the solutions of 1 mol/L HCl and 3wt% NaCl.     

Compositional dependence of thermal and elastic properties of Cu-Ti-Zr-Ni bulk metallic glasses

Starting from the quaternary Cu₄₇Ti₃₄Zr₁₁Ni₈ alloy, the compositional dependence of thermal and elastic properties of Cu-Ti-Zr-Ni alloys was systematically investigated. Quaternary Cu-Ti-Zr-Ni alloys can be cast directly from the melt into copper molds to form fully amorphous strips or rods with the thickness of 3–6 mm. The evidence of the amorphous nature of the cast rods was provided by X-ray spectra. The measured glass transition temperature (T_g) and crystallization temperature (T_x) were obtained for the alloys using differential scanning calorimetry (DSC) at the heating rate of 20 K/s. In the results, the differences between the glass temperature and the crystallization temperature (ΔT_x=T_x-T_g) are measured with values ranging up to 33–55 K. The reduced glass transition temperature (T_rg), which is the ratio of the glass temperature to the liquidus temperature (T_l), is often used as an indication of the glass-forming ability of metallic alloys. For the present Cu-Ti-Zr-Ni alloys, this ratio is typically in the range of 0.5838–0.5959, characteristic of metallic alloys with good glass-forming ability. The elastic constants for several selected alloys were measured using ultrasonic methods. The values of the elastic shear modulus, bulk modulus, and Poisson’s ratio were also given.     

含供吸电子的手性液晶聚合物的合成与性能

将有供电子基团的手性单体M1和含吸电子基团的单体M2接枝到聚甲基含氢硅氧烷上,得到系列手性液晶聚合物,其中,手性单体的摩尔分数为0～50%.通过红外光谱(IR)、核磁共振谱(1HNMR)、差示扫描量热法(DSC)、偏光显微分析法(POM)、热失重分析法(TGA)、X射线分析等手段研究了手性单体的含量及供吸基团对侧链胆甾型液晶聚合物性能的影响.结果表明P1～P8都有液晶性且为胆甾型液晶聚合物,系列液晶聚合物的tg随手性单体含量的增加而增加,ti随手性单体含量的增加而降低,P1～P8具有较宽的液晶相范围,热稳定性较高,质量损失5%时的热失重温度均在300℃左右.     

Influence of pulsing current on the glass transition and crystallizing kinetics of a Zr base bulk amorphous alloy

Based on the thermal analysis, the influence of pulsing current on the glass transition and crystallizing kinetics of Zr41.3Ti14.2CU12.8Ni10.3Be21.4 bulk amorphous alloy has been studied. The obtained results show that after the Zr41.3Ti14.2CU12.8Ni10.3Be21.4 bulk amorphous alloy was pretreated by high-density pulsing current at low temperature, its glass transition temperature Tg, the initial crystallizing temperature Tx and the corresponding exothermic peak of crystallization Tpi were reduced. But the temperature range of supercooled liquid △T=Tx-Tg is almost the same. The calculated results with Kissinger equation show that the activation energy of glass transition of the alloy pretreated is reduced significantly, while the activation energy of crystallization is basically unchanged. The influence of pulsing current on the glass transition and crystallization of theZr41.3Ti14.2CU12.8Ni10.3Be21.4 bulk amorphous alloy is believed to be related with the structure relaxation of the glass caused by the current.     

A new criterion for predicting glass forming ability of bulk metallic glasses and some critical discussions

A modified criterion,β',defined as T_g/T_x-T_g/(T_l·η))(T_g,T_x,T_l andηdenote the glass transition temperature,the onset of crystallization temperature,the liquidus temperature and constant coefficient,respectively),has been proposed for assessing the glass-forming ability(GFA) of bulk metallic glasses(BMGs).A survey of the readily available experimental data associated with the thermal analysis of various BMG alloys demonstrates that the newβ' criterion exhibits much better correlation with the GFA tha...     

联苯类液晶单体及其聚合物的合成、结构与性能

合成了4种液晶单体M1~M4和对应的聚合物P1~P4.所合成的单体及聚合物的结构与液晶性能通过了FT-IR,DSC,TGA,POM和XRD的表征.研究表明,单体M1和M2呈现互变向列相,M3呈现向列相和近晶A(SA)相、近晶C(SC)相和近晶B(SB)相,M4呈现向列相和单变SA相、SC相和SB相;聚合物P1和P2呈现向列相,P3和P4呈现SA相和向列相.末端为乙氧基的单体和聚合物比末端为乙基的单体和聚合物具有较高的熔点(tm)、玻璃化温度(tg)和液晶清亮点(ti).此外,端基柔性较好的化合物倾向于形成近晶相.聚合物P1~P4具有宽的液晶相温度范围和高的热稳定性.     

复相粘结磁体研究

研究了纳米晶Nd2Fe14B/Fe3B磁粉和铁氧体磁粉混合制备复相粘结磁体的复合效应·和稳定性的变化规律以及复合效应对复相粘结磁体密度研究了复相粘结磁体磁性能、温度系数βjHc和抗压强度的影响·结果表明,复合效应使复相粘结磁体的温度系数βjHc降低、复相粘结磁体的不可逆损失hirr减少,提高了复相粘结磁体的温度稳定性·铁氧体质量分数对100℃复相粘结磁体磁性能影响表明,剩余磁感Br和磁能积(BH)m下降,而内禀矫顽力jHc明显提高·复合效应对粘结磁体的磁性能和密度有明显的影响,而对复相粘结磁体的抗压强度影响不明显·     

氧化镧对γ-Al2O3高温比表面积的影响

为解决γ-Al2O3在高温条件下的热稳定性问题,在实验室模拟工业条件,主要从La2O3,γ-Al2O3的制备方法对γ-Al2O3的热稳定性影响进行研究.研究发现以[La(EDTA)]-为浸渍液时,[La(EDTA)]-组分的适量添加可抑制高温下γ-Al2O3比表面积的下降和向α相的转变,从而提高活性氧化铝的热稳定性,使氧化铝在高温下保持较大的比表面积.添加1%[La(EDTA)]-的样品在1 200℃焙烧10 h其比表面积达61.34 m2/g.此外,还研究了以La2O3为添加剂对γ-Al2O3样品热稳定性的影响,发现La2O3的添加未能提高样品的热稳定性.     

Preparation and thermal stability of Pd<Subscript>40.5</Subscript>Ni<Subscript>40.5</Subscript>Si<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>P<Subscript>19−<Emphasis Type="Italic">x</Emphasis></Subscript> bulk metallic glasses

With the addition of Si to replace some P, Pd_40.5Ni_40.5Si _x P_19−x (x=0, 2.5, 5, 9.5, 14, and 19 in atomic number fraction) bulk glassy samples with the diameter of about 5 mm were successfully prepared by use of flux treatment and water quenching technology. With the increase of Si content, the glass forming ability of Pd_40.5Ni_40.5Si _x P_19−x increases first for low Si content and then decreases for high Si content (Si≥9.5at%). The Pd_40.5Ni_40.5Si ₅ P₁₄ glassy alloy possesses the largest supercooled liquid region ΔT of 119 K, the largest reduced glass transition temperature of 0.621, and the largest γ parameter of 0.460, indicating that this glassy alloy possesses very large glass forming ability and very high thermal stability.