非晶合金的热稳定性与热加工窗口研究

采用铜模喷铸法制备了Mg_(68)Zn_(28)Ca_4、Cu_(47)Ti_(34)Zr_(11)Ni_8和Zr_(60)Nb_5Cu_(20)Fe_5Al_(10) 3种非晶合金,通过X射线衍射仪(XRD),差热分析仪(DSC)研究了非晶合金的热加工稳定性,并建立了三维热加工窗口。结果表明,Mg68Zn28Ca4的过冷液相区没有明显随着加热速率的增大向高温区移动,Cu_(47)Ti_(34)Zr_(11)Ni_8和Zr_(60)Nb_5Cu_(20)Fe_5Al_(10)非晶合金的过冷液相区随着加热速率的增大向高温区移动。用Kissinger方法计算出3种非晶的晶化激活能分别为177.26,288.98和288.75kJ/mol。根据建立的三维热加工窗口中可以直接制定非晶合金的加工工艺,确定加工温度及最大加热时间。     

CuZr基块体非晶合金室温拉伸力学性能研究

由于受到制备尺寸和材料特性的限制,目前块体非晶合金力学性能的研究多集中在压缩力学性能的相关研究。选取Zr_(47)Cu_(46)Al_6Co_1块体非晶合金,研究该合金在室温条件下拉伸力学性能。实验结果表明,样品的拉伸断裂强度约为2 000 MPa,其断裂方式为无征兆的脆性断裂,断口表面光滑平整。其断口主要形貌为放射状的河流花纹,该图案是非晶合金拉伸断裂的典型形貌。根据样品的断口形貌观察,可以推断Zr_(47)Cu_(46)Al_6Co_1块体非晶合金室温拉伸断裂的方式与传统非晶合金拉伸断裂方式相一致。     

La 对非晶 Ni_(63)Zr_(37)合金表面状态的影响

采用俄歇电子能谱和 X 射线光电子能谱,并结合氩离子原位溅射剥层研究了非晶 Ni_(63)Zr_(37)及Ni_(63)Zr_(32)La_5合金条带自由侧和贴辊侧的表层成分分布及元素的化学状态。结果表明,非晶 Ni_(63)Zr_(37)合金条带贴辊侧氧化层较自由侧厚且 Zr 的表面偏聚较为显著;加入 La 后,显著地改变了 Ni_(63)Zr_(37)合金条带两侧的表面状态;在合金条带表面及近表面,Ni 以金属态弥散分布在 Zr 和 La 的氧化物上,其电子状态受氧化物的影响;条带表层 Zr 的氧化物由 ZrO_x(1相似文献   

ZrCuNiAlEr块体金属玻璃尺度效应的研究

通过磁悬浮熔炼-铜模吸铸法制备了直径为2,4,6 mm的(Zr_(63.36/100)Cu_(14.25/100)Ni_(10.12/100)Al_(12/100))_(100-x)Er_x(x=0.5,1,1.5,2,2.5,3)块体金属玻璃棒状试样,研究了尺寸大小对合金力学性能的影响。结果表明,当x=2,2.5时,直径为2 mm的合金试样出现了大的压缩塑性变形,塑性变形量分别达到24.59%和24.93%。而?4和6mm合金试样的压缩塑性变形基本上无变化,这就说明该非晶合金的塑性随着尺寸的增大而下降,即非晶合金压缩塑性存在尺寸效应。弹性模量、屈服强度和断裂强度也随着合金尺寸的增加而下降,即随着非晶合金尺寸的增加其力学性能逐渐降低。     

全金属组元铁基块体非晶的制备与性能研究

为了获得良好的玻璃形成能力,通常在铁基非晶合金中添加类金属元素(P、C、B、Si等),但这些铁基非晶合金大多室温塑性很差,且其脆性与其类金属元素的种类、含量以及分布有密切关系,因而本文选取全金属组元铁基非晶合金(Fe_(0.52)Co_(0.3)Ni_(0.18))_(73)Cr_(17)Zr_(10),通过旋淬甩带与铜模喷铸的方法分别制备了条带与块体试样,并采用X射线衍射仪(XRD)、差示扫描量热仪(DSC)、万能试验机等进行了相关性能研究.研究表明:(Fe_(0.52)Co_(0.3)Ni_(0.18))_(73)Cr_(17)Zr_(10)的临界尺寸在1～2 mm,玻璃转变温度为482℃,过冷液相区达到70℃;直径为1 mm的非晶棒材的屈服强度为2 190 MPa,断裂强度达到2 800 MPa,塑性应变量为3.6%.全金属成分中更多的金属-金属键合方式可能是其拥有较好塑性的原因.     

Y元素的添加对Zr_(56)Co_(28)Al_(16)非晶合金在模拟体液中耐蚀性能的影响

采用铜模吸铸法制备了(Zr_(56)Co_(28)Al_(16))_(100-x_Y_x(x=0,1,2,4)非晶合金,研究了(Zr_(56)Co_(28)Al_(16))_(100-x)Y_x(x=0,1,2,4)非晶合金在模拟体液(PBS溶液)中的耐蚀性。运用X射线衍射(XRD)表征试样的结构,运用电化学工作站、场发射扫描电镜(SEM)和X射线光电子能谱(XPS)研究Y元素的添加对Zr_(56)Co_(28)Al_(16)非晶合金耐蚀性的影响。结果表明,适量Y元素的添加显著提高了Zr_(56)Co_(28)Al_(16)非晶合金的耐蚀性,但过量Y元素的添加,在非晶基体上有晶体相的析出,降低了Zr_(56)Co_(28)Al_(16)的耐蚀性能。     

Gibbs Free Energy and Activation Energy of ZrTiAlNiCuSn Bulk Glass Forming Alloys

The Gibbs free energy differences between the supercooled liquid and the crystalline mixture for the (Zr_(52.5)Ti_5Al_(10)-Ni_(14.6)Cu_(17.9))_((100-x)/100)Sn_x (x=0, 1, 2, 3, 4 and 5) glass forming alloys are estimated by introducing the equationproposed by Thompson, Spaepen and Turnbull. It can be seen that the Gibbs free energy differences decrease firstas the increases of Sn addition smaller than 3, then followed by a decrease due to the successive addition of Snlarger than 3, indicating that the thermal stabilities of these glass forming alloys increase first and then followed by adecrease owing to the excessive addition of Sn. Furthermore, the activation energy of Zr_(52.5)Ti_5Al_(10)Ni_(14.6)Cu_(17.9) and(Zr_(52.5)Ti_5Al_(10)Ni_(14.6)Cu_(17.9))_(0.97)Sn_3 was evaluated by Kissinger equation. It is noted that the Sn addition increases theactivation energies for glass transition and crystallization, implying that the higher thermal stability can be obtainedby appropriate addition of Sn.     

激光3D打印非晶合金晶化体积分数的理论预测

采用一种有效的方法预测激光3D打印块状非晶合金的晶化程度,对于激光3D工艺参数的选择与优化至关重要。本工作从非晶合金的晶化动力学入手,通过测试不同加热速率下非晶合金的特征温度,获得非晶合金发生晶化所要克服的晶化激活能和Arrhenius指前因子,并结合有限元模拟技术,提出了一种预测激光3D打印非晶合金晶化体积分数的方法。以Zr_(50)Ti_5Cu_(27)Ni_(10)Al_8(Zr50)非晶合金为模型体系,验证了该方法的有效性。结果表明:利用该方法获得的激光3D打印单道Zr50非晶合金晶化相体积分数为1.23%,与实验得到的晶化相体积分数1.65%较接近,这有力地证明了提出的激光3D打印非晶合金晶化体积分数的理论预测方法是可行的。     

粉末冶金(FeNiMnAl_(x))_(50)Cu_(50)中熵合金的微观组织与力学性能EI北大核心CSCD

对物理法制备的再生铜合金粉末进一步合金化,通过机械合金化(MA)结合放电等离子烧结(SPS)的方法制备了(Fe_(40)Ni_(40)Mn_(20))_(50)Cu_(50),(Fe_(38)Ni_(38)Ni_(38)Mn_(19)Al_(5))_(50)Cu_(50),(Fe_(36)Ni_(36)Mn_(18)Al_(10))50 Cu_(50)和(Fe_(32)Ni_(32)Mn_(16)Al_(20))_(50)Cu_(50)四种中熵合金块体,并研究了Al元素的含量对中熵合金微观组织与力学性能的影响。结果表明:在高能球磨60 h之后合金粉末完成合金化,四种中熵合金粉末均形成单一FCC相的过饱和固溶体且有微量WC杂质。经SPS烧结后,(Fe_(40)Ni_(40)Mn_(20))_(50)Cu_(50),(Fe_(38)Ni_(38)Mn_(19)Al_(5))_(50)Cu_(50)和(Fe_(36)Ni_(36)Mn_(18)Al_(10))50 Cu_(50)形成了由富Cu的FCC1相和富Fe-Ni的FCC2相组成的双相FCC结构,并具有超细晶+微米晶的多尺度结构;而(Fe_(32)Ni_(32)Mn_(16)Al_(20))_(50)Cu_(50)由富Cu的FCC主相和少量富Fe-Mn的FCC2相及富Ni-Al的BCC相(B2)组成。随着Al含量的提高,四种中熵合金的塑性逐渐降低,而强度和硬度逐渐提高。(Fe_(40)Ni_(40)Mn_(20))_(50)Cu_(50)合金的压缩屈服强度、抗压强度和维氏硬度分别为878 MPa,1257 MPa和248.5HV。与(Fe_(40)Ni_(40)Mn_(20))_(50)Cu_(50)相比,(Fe_(32)Ni_(32)Mn_(16)Al_(20))_(50)Cu_(50)的压缩屈服强度和硬度分别提高了50.1%和50.4%,断裂应变由19.55%下降至8.31%。     

铜模吸铸法制备的Fe74Al4Sn2P10Si4B4C2块体非晶与块体纳米晶合金

利用铜模吸铸法制备了直径φ1.0mm和2.0mm的Fe74Al4Sn2P10Si4B4C2块体非晶合金和直径2.0mm的Fe74Al4Sn2P10Si4B4C2块体纳米晶合金圆棒.利用X射线衍射、差示扫描量热仪(DSC)和差热分析仪(DTA)对Fe74Al4Sn2P10Si4B4C2块体非晶合金的结构和热性质进行了测定.该非晶合金的超冷液相区△Tx为16.7K,约化玻璃转变温度Tg/Tm和Tg/T1分别为0.60和0.57.Fe74Al4Sn2P10Si4B4C2合金接近共晶成分,在10K/min的冷却速率下其过冷度可达86.7K.利用透射电子显微镜(TEM)观察了制备态的Fe74Al4Sn2P10Si4B4C2纳米晶合金圆棒的结构,为非晶基体上均匀分布的尺寸10～20nm的α-Fe晶粒.Fe74Al4Sn2P10Si4B4C2合金能达到较大的过冷度,具有较高的约化玻璃转变温度(接近共晶合金成分)和过冷合金熔体的二步相析出有利于块体非晶合金和块体纳米晶合金的形成.铜模吸铸法既可制备块体非晶合金,也可制备块体纳米晶合金,是一种很有吸引力的制备块体非晶合金和块体纳米晶合金的方法,并进一步证实利用快速凝固法可以直接制备块体纳米晶合金.     

Pressure Effect on Crystallization of Zr55Cu30Al10Ni5 Bulk Metallic Glass

The effect of pressure on the variation of the crystallization phases of the Zr55u30Al10Ni5 bulk glass and its thermal stability under high pressure annealing was investigated by X-ray diffraction (XRD)and differential scanning calorimeter(DSC).The mode of crystallization and products of crystallization of the Zr55Cu30Al10Ni5 bulk glass were quite different pressure.At ambient pressure,the crystallization products consisted of NiZr2 and CuZr2,while at pressure of 1 Gpa and 3 Gpa,the alloys crystallized into NiZr2 and Cu10Zr7,respectively.The alloy was nearly not crystallized and only a small amount of Cu10Zr7 was precipitated under 5 Gpa.DSC proved that the mode of the crystallization under high pressure was different from that at ambient pressure.     

大块非晶合金Zr55Cu30Al10Ni5的电子结构特征及电击穿行为

测定了大块非晶合金Zr55Cu30Al10Ni5晶化前后的费米能级和各元素的电子结合能,研究了非品合金的电子结构特征和电击穿行为．测试并讨论了非晶材料场发射能力和耐电压强度的关系．结果表明,对于Zr基合金,非品态比品态合金具有更大的功函数．比较了Zr55Cu30Al10Ni5合金非晶态与晶态的耐电压强度数值,发现非晶态合金的耐电压强度数值比较分散,品化合金的耐电压强度相对比较集中．耐电压强度平均值表明,Zr基合金非晶态具有更好的耐电压能力．     

Friction Stir Welding of Zr_(55)Al_(10)Ni_5Cu_(30) Bulk Metallic Glass to Crystalline Aluminum

The Zr55Al10Ni5Cu30 bulk metallic glass plate were successfully welded to crystalline aluminum plates by using a friction stir welding (FSW) method. The welded zone was examined. No defects, cracks or pores were observed and no other crystalline phases except for aluminum were found in the welded joint. The strength of the joint is higher than that of aluminum. The glassy phase in the stir zone keeps the amorphous state, showing a successful welding. The storage modulus softens over the glass transition. An...     

Crystallization Behavior of Zr_(55)Al_(10)Cu_(30)Ni_5 Bulk Metallic Glass Rolled at Room Temperature

Zr 55 Al 10 Cu 30 Ni 5 bulk metallic glass was rolled up to 95% in thickness reduction at room temperature, and the dependences of microstructure and thermal stability on the strain were investigated. It is revealed that phase transformations do not occur during the rolling, but the split of the crystallization peaks becomes more and more obvious with increasing thickness reduction. Analyses of the radial distribution functions and the pair correlation functions indicate that the rolling has enhanced the sh...     

Dynamic mechanical relaxation behavior of Zr35Hf17.5Ti5.5Al12.5Co7.5Ni12Cu10 high entropy bulk metallic glass

Non-equiatomic high entropy bulk metallic glasses were reported recently and show unique mechanical and physical properties.Dynamic mechanical relaxation behavior of Zr35Hf17.5Ti5.5Al12.5C07.5Ni12Cu10 high entropy bulk metallic glass was investigated by dynamic mechanical analysis(DMA)and the mechanical spectra could be well described by the quasi-point defects(QPD)theory.Compared to typical metallic glasses,the intensity of the β relaxation of Zr35Hf17.5Ti5.5Al12.5Co7.5Ni12Cu10 high entropy bulk metallic glass is lower due to the sluggish diffusion.At the same time,the correlation factor χ is higher than that of conventional metallic glasses and this is ascribed to the high configuration entropy.In paral-lel,physical aging below the glass transition temperature leads to a decrease of atomic mobility,caused by a decrease of the concentration of defects.     

超声波筛选激光增材制造非晶合金

目的 快速优化出无缺陷非晶合金激光增材制造工艺。方法 以Zr51Ti5Cu25Ni10Al9非晶合金为模型材料,利用超声波对金属内部缺陷的衰减,来快速筛选激光增材制造非晶合金的最佳工艺组合(激光功率和扫描速度)。结果 超声波检测可以准确有效地检测出非晶合金试件的晶化比例,并且当激光功率为1 300 W、扫描速度为600 mm/min时超声波衰减系数降至最低。进一步对该工艺下获得的样品分析发现,该工艺成型的Zr51Ti5Cu25Ni10Al9非晶合金缺陷最少、晶化程度最低、性能最佳。结论 超声波技术是快速筛选激光增材制造非晶合金等高性能金属最佳工艺参数的有效技术手段。     

Fabrication of Cu rich bulk metallic glass composites via solidification method

Abstract

Cu based bulk metallic glasses and composites with tiny crystalline phases embedded in metallic glass matrix have been successfully fabricated by solidification technique in the present work. The formation of crystalline phases and structure inhomogeneity in bulk metallic glasses was characterised. Al is used as the minor alloying element to partly substitute Cu element in 61Cu–34Zr–5Ti. The results show that quarternary 60Cu–34Zr–5Ti–1Al alloy exhibits monoamorphous feature, and 56Cu–34Zr–5Ti–5Al alloy has a few crystalline peaks superimposed on a broad diffraction peak, suggesting that a composite structure forms in certain solidification conditions. To further identify the microstructure of the as cast rod, all samples were characterised by scanning electron microscopy (SEM). Small size phases are found in 2 mm diameter 56Cu–34Zr–5Ti–5Al rod, which has larger plastic deformation. The composition of those crystalline phases is also investigated. All results indicate that the presence of certain phases in metallic matrix benefits the mechanical properties of the as cast bulk metallic glasses.     

锆基大块非晶合金及其晶化合金在0.5mol/L H2SO4中的腐蚀行为研究

根据合金的DSC曲线制定了Zr60Al15Ni25、Zr52.5Al10Ni10Cu15Be12.5和Zr65Al10Ni10Cu15等锆基大块非晶合金的等温退火工艺,获得了与非晶态合金具有相同成分的晶化合金。通过研究非晶态合金和晶化合金在0.5mol/L H2SO4中的极化曲线,结合扫描电镜(SEM)和能量散射X射线谱(EDS)分析,发现,在0.5mol/LH2SO4中非晶态合金和晶化合金都具有非常优异的耐腐蚀性能,但非晶合金的耐腐蚀性能要比晶化合金稍好。这主要是因为晶态合金的结构中不存在晶界、位错等缺陷,同时非晶态合金中的组元具有很高的活性,使合金更快地进入钝态。     

用渗流铸造法制备Zr55Al10Ni5Cu30非晶复合材料

用渗流铸造法制备出以Zr55Al10Ni5Cu30合金为基体，以W丝束为增强相的大块非晶复合材料，采用X-射线衍射分析了基体的相组成，在扫描电镜（SEM）下观察了反应界面的形貌，利用电子探针研究了元素的迁移情况，通过改变渗流温度和时间。研究了W丝和基体间界面的作用过程，选择适当的渗流温度和时间，可以制备出长65mm直径4.3mm的大块W丝束增强Zr55Al10Ni5Cu30非晶复合材料，在一定范围内提高渗流温度降低渗流时间或降低渗流温度延长渗流时间能得到同样的结果，在渗流铸造前，液态金属的过热有利于提高基体的非晶形成能力，降低渗流铸造时产生的缺陷。     

Microstructure Evolution of Zr50Cu18Ni17Al10Ti5 Bulk Metallic Glass during Cold-rolling

Zr50Cu18Ni17Al10Ti5 bulk metallic glass has been rolled at room temperature up to 95% in thickness reduction, and the dependence of microstructure on the strain was investigated. With increasing thickness reduction, the full width at half maximum (FWHM) and crystallization enthalpy decrease gradually till 80%, and then increase evidently at 95%. It is revealed that the reversible transition between the ordered and disordered atomic configurations was found in the metallic glass as the deformation proceeds, which is further verified by the high-resolution transmission electron microscopy images. The final microstructure in metallic glass during cold-rolling is the net result of two competing processes between shear-induced disordering and diffusion controlled reordering.