Al_(91)Ni_7Y_2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 Al91 Ni7Y2 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 Al91 Ni7Y2 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 2 40℃和 2 6 7℃ (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     

Crystallization process in rapidly solidified Al-Nd-Ni amorphous alloy prepa red by melt spinning

1　INTRODUCTIONIntherecentfew years ,Al richmetallicglasshasbeenpaidmoreandmoreattentiontointhenovelmaterialsresearchfield ,notonlyduetoitshighstrength ,hardnessandlowdensity ,butalsobecauseanew typeAl basednanophasecompositecanbeob tainedfromitbypartialcrystallization[17] .ManyAl basedamorphous/nanocrystallinealloyscontainingrareearth(RE =La ,Y ,Ce ,Nd ,etc)andtransitionmetal(TM =Fe ,Co ,Ni,etc)elementshaveanattractivecombinationofmechanicalproper ties .Ithasbeenreportedthatmanyofth…     

Mg60Cu30Y10块体非晶合金的变温晶化行为

采用示差扫描量热仪(DSC)得到Mg60Cu30Y10块体非晶合金在不同加热速率下的DSC曲线。利用Losocka、Kissinger以及Doyle方法研究了Mg60Cu30Y10块体非晶合金的非等温晶化动力学。结果表明:Mg60Cu30Y10块体非晶合金具有良好的热稳定性。通过Kissinger方法计算得到的其玻璃转变激活能(Eg)、晶化激活能(Ex)以及晶化峰值激活能(Ep)分别为160.07 kJ/mol、136.11和145.19 kJ/mol。随着加热速率的提高,各特征温度值向高温端移动。局域晶化激活能随着复合材料晶化体积分数的增加先增大后减小。     

Crystallization kinetics of amorphous Zr65Cu25Al10 alloy

1　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｄｅｖｅｌｏｐｍｅｎｔｏｆｇｌａｓｓｆｏｒｍｉｎｇ ｍｕｌｔｉｃｏｍｐｏ ｎｅｎｔａｌｌｏｙｓｙｓｔｅｍｓｗｉｔｈｖｅｒｙｌｏｗｃｒｉｔｉｃａｌｃｏｏｌｉｎｇｒａｔｅｓｗｉｔｈｉｎ 1～ 10 0Ｋ/ｓｈａｓｏｆｆｅｒｅｄｆｉｒｓｔ     

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     

超声振动对含LPSO结构的Mg98Y1.0Ni0.5Al0.5合金显微组织与力学性能的影响(英文)

低Y、Ni含量的LPSO结构增强镁合金具有低成本、优异力学性能的特点。为进一步提升其综合力学性能,掺杂Al元素及熔体超声振动处理是可行的途径。通过扫描电子显微镜、能谱分析、透射电子显微镜、X射线衍射和纳米压痕测试研究掺杂Al元素后低Y、Ni含量的Mg98Y1.0Ni0.5Al0.5合金的显微组织,对比超声振动对显微组织与力学性能的影响。掺杂Al后LPSO结构的含量降低,且在块状LPSO结构相邻处析出圆整的Al₂NiY相。Al₂NiY相与LPSO结构和Mg基体在界面处均不共格。通过对熔体施加超声振动处理后,Al₂NiY相被有效细化为短片状,并均匀分布在基体中,阻碍微裂纹的产生和扩展,从而提高Mg₉₈Ni_0.5Y_1.0Al_0.5合金的力学性能。与未经超声处理Mg₉₈Ni_0.5Y_1.0Al_0.5合金相比,其极限抗拉强度和伸长率提升至187 MPa和7.9...     

Zr41.2Ti13.8Cu12.5Ni10Be22.5合金凝固过程热力学

利用真空冷壁坩埚感应熔炼及铜模离心铸造的方法制备了大尺寸非晶态Zr41．2Til3．8Cul2．5Ni10Be22．5材料，采用DTA和DSC分别研究了该合金的凝固特性及非晶态晶化行为。结果表明：Zr41．2Til3．8Cul2．5Ni10Be22．5合金具有较低的熔点，表现出良好的深共晶特性，在较低的冷却速度下即可制备出大块部分非晶及全部非晶材料。Zr41．2Til3．8Cul2．5Ni10Be22．5大块非晶材料在339．5℃发生玻璃转变，晶化温度为420℃。     

Crystallization behavior of amorphous Zr70Cu20Ni10 alloy annealed at 380℃

Crystallization behavior of amorphous Zr70Cu20Ni10 alloy isothermally annealed at 3800℃ was first investigated by employing the differential scanning calorimetry (DSC) and transmission electron microscopy(TEM). It has been found that an exothermic peak appears in the DSC trace when the annealing time is about 17-18min,in dicating a certain phase transformation occurs in the matrix of amorphous Zr70 Cu20 Ni10 alloy.Meanwhile,isothermal annealing experiments for amorphous Zr70Cu20Ni10 alloy ranging from 370℃ to 400℃with a temperature interval of 10℃ were also carried out,from which no exothermic reaction can be observed except for the case of 380℃.This behavior indicates that the phase transformation during isothermal annealing of amorphous Zr70Cu20Ni10 alloy is strongly temperature-and time-dependent.Further investigations are required to reveal the nature of such phenome non.     

稀土元素Y、Nd对AZ81镁合金组织和高温性能的影响

研究了稀土元素Y、Nd对AZ81镁合金组织和高温力学性能的影响。结果表明，稀土元素Y、Nd的加入明显细化了AZ81镁合金的显微组织，减少了β（Mg17Al12）相的析出。分析认为，稀土元素Y和Nd主要是通过固溶强化、析出强化和细晶强化提高了合金的室温和高温强度，改善了合金的塑性。复合加入2％的Y和Nd，合金的室温强度最高，达282．5MPa，与未加稀土的AZ81相比，约提高了39％。含1％Y的AZ81合金在150℃下的高温强度高达220MPa，与不含稀土的AZ81相比高温强度约提高40％。     

Zr65Al7.5Cu17.5Ni10大块非晶态合金的制备及晶化过程

采用直接水淬法成功制备直径５ｍｍ球状Ｚｒ６５Ａｌ７．５Ｃｕ１７．５Ｎｉ１０大块非晶态合金。Ｘ射线衍射、透射电镜检验证明样品完全为非晶态。采用Ｘ射线衍射、差示扫描热分析仪（ＤＳＣ）分析了Ｚｒ６５Ａｌ７．５Ｃｕ１７．５Ｎｉ１０非晶态合金的晶化过程,利用Ｋｉｓｓｉｎｇｅｒ方程求得Ｚｒ６５Ａｌ７．５Ｃｕ１７．５Ｎｉ１０非晶合金的晶化表观激活能。Ｘ射线衍射实验结果表明,Ｚｒ６５Ａｌ７．５Ｃｕ１７．５Ｎｉ１０非晶态合金的晶化是按下面的次序进行的,非晶态合金→体心立方晶相Ｚｒ２（Ｎｉ,Ａｌ）＋非晶相→体心立方相Ｚｒ２（Ｎｉ,Ａｌ）＋体心立方相Ｚｒ２（Ｃｕ,Ａｌ）。     

稀土钇和钕对挤压ZK60合金组织及拉伸性能的影响

研究了添加稀土Y 1wt%和Nd 1wt%对挤压态ZK60合金组织及拉伸性能的影响。结果表明,稀土的添加可有效细化ZK60镁合金的挤压态组织,Y、Nd复合添加的细化效果更为显著,平均晶粒直径为2~3μm;稀土Nd的添加使ZK60合金的析出相尺寸增大,复合添加稀土Y、Nd后,ZK60合金中析出相数量增多、尺寸减小且分布均匀;Y、Nd的复合添加可使ZK60合金的抗拉强度与屈服强度分别提高8.4%与31.2%,这归因于复合添加Y、Nd形成的细晶强化、固溶强化及析出相强化的综合影响。     

Mg70Ni15Gd10Ag5块体非晶的制备及晶化行为

采用铜模铸造法制备新型块体非晶合金Mg70Ni15Gd10Ag5(at%),其临界制备尺寸不低于5 mm,是目前Mg-Ni基非晶合金制备尺寸的最大值。采用差示扫描量热（DSC）法研究非晶合金的晶化行为,发现合金的晶化为多级晶化。随着升温速度的提高,玻璃转变温度Tg、晶化开始温度Tx、熔化前4个放热峰温度（Tp1、Tp2、Tp3、Tp4）、熔化开始温度（Tm）和液相线温度（Tl）均向高温区移动,晶化行为具有显著的动力学特征。利用Kissinger法计算特征温度对应的激活能,其值分别为Eg=188.05 kJ/mol、Ex=144.79 kJ/mol、Ep1=138 kJ/mol、Ep2=142.40 kJ/mol、Ep3=119.10 kJ/mol、Ep4=72.86 kJ/mol。     

喷射成形La62Al15.7(Cu,Ni)22.3块体非晶合金的晶化行为

研究了喷射成形和铜模吸铸法制备的La62Al15.7(Cu,Ni)22.3块体非晶合金的晶化行为。结果表明,两种工艺制备的非晶合金晶化过程都为三级晶化,晶化的顺序为:非晶→非晶+La→非晶+La+Al3La→非晶+La+Al3La+富Cu和Ni的未知相。结合晶化动力学计算和退火晶化实验结果表明,低温(<503K)时,喷射成形La62Al15.7(Cu,Ni)22.3非晶合金的热稳定性优于铜模吸铸La62Al15.7(Cu,Ni)22.3非晶合金,高温(>553K)时结果相反。     

Effect of heat treatment conditions on microstructure and wear behaviour of Al4Cu2Ni2Mg alloy

Al4Cu2Ni2Mg alloy is an age-hardenable aluminum alloy. The effect of different solution and aging heat treatment conditions on the microstructure, hardness and wear resistance of the alloy was studied. The cast specimens were solution treated and then artificially aged. Optical microscopy and scanning electron microscopy were used to investigate the microstructures of the specimens. The hardness and wear tests were applied to understanding the effects of heat treatment. After aging for 8 h, the hardness of the alloy increases from HV₁₀ 96.5 to 151.1. Aging treatment for a longer duration causes a drop in the hardness because of over aging. Increasing the hardness of the alloy increases the wear resistance. As a result of all tests, solution heat treatment at 540 °C for 8 h and aging at 190 °C for 8 h were chosen for optimum heat treatment conditions for this alloy.     

Applicability of Johnson-Mehl-Avrami model to crystallization kinetics of Zr60Al15Ni25 bulk amorphous alloy

The applicability of Johnson-Mehl-Avrami（JMA） model to the crystallization kinetics of Zr60Al15Ni25 bulk amorphous alloy is investigated by differential scanning calorimetry（DSC） under isochronal and isothermal conditions. A criterion Xm, at which a defined function z（x） exhibits the maximum value, is introduced to check the validity of JMA model to the kinetics analysis. The value Of Xm has a constant of 0.632 for JMA model. It is found that the values Of Xm at different isothermal annealing temperatures （743,748, 753 and 758 K） are almost near 0.632, which indicates that the isothermal crystallization kinetics can be modeled by JMA equation. However, the values Of Xm at different heating rates （10, 20, 30 and 40 K/min） are about 0.52, implying that JMA model is not valid to the isochronal crystallization kinetics. The reason why the JMA model is not valid to the isochronal crystallization kinetics is discussed.     

Stability of amorphous Al90TMxCe10—x（TM=Fe or Ni） alloys

X-ray diffraction(XRD) and differential scanning calorimetry(DSC) were used to investigate the crystallization process of amorphous Al90TMxCe10-x (atom fraction in%;TM=Fe or Ni;x=3,5)alloys,Aging effects were examined by X-ray diffraction,The structure corresponding to the prepeak for the amorphous Al90Fe5Ce5 alloy is more stble than the amorphous matrix,but it is not stable for amorphous Al90Ni5Ce5 alloy during the first crystallization stage and even decomposes at room temperature,Although both Al-Ni and Al-Fe have strong chemical bonding,the cyrstallization onset temperature of amorphous Al-Fe-Ce alloys is much higher than that of amorphous Al-Ni-Ce alloys,which is likely caused by the different stability of the structure corresponding to the prepeak.The crystallization onset temperature increases as Ce/Ni ratio increases in amporphous Al90NixCe10-x alloys,whereas it decreases as Ce/Fe ratio increases in amorphous Al90FexCe10-x alloys.A better atomic packing produces as Ce content increases because of the size mismatch in Al-Ni-Ce systems and as Fe content increases because of the increasing Fe central structural units.     

Mg_(65)Cu_(25)Y_(10)块体非晶合金的晶化组织(英文)

将普通铜模浇铸法制得的Mg65Cu25Y10块体非晶合金试样置于200°C进行保温处理,对处理后的试样的相组成和显微组织进行研究。XRD分析结果表明,该块体非晶的晶化随保温时间的延长趋于完全,在此过程中有Mg2Cu、Mg24Y5和HCP-Mg等晶体相析出。通过SEM观察到雪花状组织,EDS结果表明该雪花状组织的成分接近于铸态合金的成分,TEM分析表明其为层片状结构。电子衍射花样分析表明,雪花状组织由Mg24Y5晶体和非晶相组成。在保温过程中,基体中的FCC-Mg会转变为HCP-Mg。     

Fe68Nd5Zr2Y4B21大块非晶合金磁性能的研究

采用铜模吸铸法制备出厚度为0.8 mm的片状Fe68Nd5Zr2Y4B21大块非晶合金.利用X射线衍射(XRD),差热分析(DTA)和振动样品磁强计(VSM)研究了Fe68Nd5Zr2Y4B21大块非晶合金在铸态和不同温度退火后的磁性能.结果表明,Fe68Nd5Zr2Y4B21大块非晶合金在铸态下为软磁性.合金晶化退火后,磁性能转变为硬磁性,得到了块状的纳米晶复合永磁材料.合金硬磁性的产生是由于合金晶化后产生了Nd2Fe14B硬磁性相和α-Fe,Fe3B软磁性相,软、硬磁相间产生了较强的交换耦合作用而造成的.这一方法为制备块体纳米晶复合永磁材料提供了一种新的手段.     

Co/Ni比对FeCoNiCrZr非晶合金变温晶化行为的影响

采用单辊急冷法制备了一系列不同Co/Ni比的FeCoNiCrZr非晶薄带,用Kissinger和Ozawa法研究Co/Ni比的变化对(Fe0.52Co0.48-xNix)73Cr17Zr10系非晶合金变温晶化行为的影响。结果表明:x在0.06~0.30变化时,所制备的合金薄带基本上以非晶结构为主;随着Co/Ni比的增加,特征温度Tg、Tx、Tp均向高温区移动;由于不同升温速度下特征温度对应的晶化体积分数几乎不变,因而,采用Kissinger法与Ozawa法的计算结果非常接近,且都呈现Eg﹥Ex﹥Ep的规律;随着Ni含量的增加,Ex呈先增大后减小的趋势。合金的阶段晶化激活能Eo随晶化分数x的增加而逐渐下降。     

Cu对非晶Fe74Al4Ga2P12B4Si4合金晶化行为的影响

研究了Fe74Al4Ga2P12B4Si4和Fe73Al4Cu1Ga2P12B4Si4合金在500～550℃的等温晶化行为,并分析了Cu对Fe74Al4Ga2P12B4Si4合金晶化行为的影响.采用XRD和DSC分析晶化相组成.结果表明,Cu降低合金的晶化温度,使得DSC图像上的玻璃转变温度消失,在铸态组织中出现淬态核.同时Cu的富集为α-Fe的形核提供大量的形核中心,阻止晶粒的长大,使合金纳米化,改变了合金的晶化方式和最终晶化产物.