镁基大块非晶合金在深过冷液相区的塑性变形

研究了Mg65Cu25Y7Nd3大块非晶合金在玻璃转化温度Tg附近及深过冷液相区的等温压缩变形行为。结果表明，Mg65Cu25Y7Nd3大块非晶合金的塑性变形与加热温度和加载时间紧密相关。在423K时该大块非晶合金具有一定的塑性，而在深过冷液相区则具有良好的塑性。通过系列试验，得出了Mg65Cu25Y7Nd3大块非晶合金的最佳加热温度为443～463K，加载时间约10min。对大块非晶合金在变形过程中的结构变化的分析表明，在本试验条件下，压缩变形对Mg65Cu25Y7Nd3大块非晶合金的晶化过程没有明显的影响。     

镁基大块非晶合金在过冷液相区流变行为本构关系

研究了Mg60Cu30Y10大块非晶合金在过冷液相区的流变行为.结果表明:随着温度升高和应变速率增加,平衡态的牛顿流转变为非平衡态的非牛顿流;其流变行为对于温度和应变速率非常敏感.由粘度与应变速率的关系,根据Arrhenius型VFT方程,确定了流动应力、应变速率和温度的关系.Mg60Cu30Y10大块非晶合金在过冷液相区的流变性能依赖于温度与变形速率,其微观机制可由自由体积模型解释,为大块非晶合金流变成形工艺的实现提供理论依据:温度高于玻璃转变温度以后,自由体积的增加使非晶合金变形过程中能够移动的原子数目随之增加,自由体积周围的原子沿外力的作用方向移动,即宏观上的塑性流变行为.应变速率增加,由热激活引起的自由体积增加不能满足更多原子流变所需的空间体积,导致牛顿流向非牛顿流转变.     

块体金属玻离的开发和应用

过渡金属基块体金属玻璃 下表列出了过渡金属基块体金属玻璃的主要特性。Pt-Pd-Cu-P块体玻璃合金具有很低的Tg（约500K）、宽广的过冷液相区（〉90K）和高的耐蚀性。很适于在过冷液相区粘滞流变加工。日本东北大学开发的水雾化制粉技术，能够大量生产粒度自0．1至2mm的Fe基玻璃合金，月生产能力达20t。     

Ti-Cu-Ni三元大块非晶合金的制备与力学性能

采用铜模喷铸法成功制备出成本较低、直径为2 mm的Ti基Ti50Cu42Ni8大块非晶合金.利用XRD、DSC及SEM等手段研究了Ti50Cu50-xNix(x=5, 8, 11)合金的非晶形成能力、力学性能与变形行为.结果表明:Ti50Cu42Ni8大块非晶合金具有明显且较高的玻璃转变温度Tg(659 K)、晶化初始温度Tx(716 K)、宽的过冷液相区ΔTx=Tx－Tg(57 K)、高的约化玻璃转变温度Trg=Tg/Tm(0.565)和压缩断裂强度(2008 MPa).     

Ti53Cu27Ni12Hf3Al7Si3B1大块金属玻璃的制备及性能研究

用单辊甩带法和铜模铸造法制备了新型Ti基大块金属玻璃Ti53Cu27Ni12Hf3Al7Si3B1.DSC、DTA研究表明该合金具有较高的热力学稳定性,其第1晶化温度Tx1、玻璃转变温度Tg、过冷液相区间ΔTx以及约化转变温度Trg分别为705、750、45、0.63 K.压缩性能研究其压缩断裂强度、弹性模量和压缩塑性变形量分别为2 304 MPa、120 GPa和1.1%.研究发现,具有复杂拓扑结构的原子配比提高了Ti53Cu15Ni18.5Al7Hf3Si3B0.5大块金属玻璃的力学性能和热力学性能.     

大块非晶态合金的开发和应用

大块非晶态合金的形成和特性 最近日本东北大学金属材料研究所所长井上明久教授就利用大过冷液相相变开发出的高性能非晶或大块非晶(亦称金属玻璃)材料进行了综合性介绍。金属或合金从液体急冷凝固或缓冷凝固制取了非晶或大块非晶材料已成为材料界瞩目的焦点。提高过冷液体的稳定性，在100K／s冷速下可获取二维以下的薄带、     

大块非晶合金的超塑性研究进展

对大块非晶合金在过冷液相区内的超塑性变形特点进行了评述.介绍了在过冷液相区内的流变行为和变形后的组织结构变化,并解释了超塑性变形的机理.同时,对大块非晶合金的超塑性成形技术发展现状况进行了概述.     

大块非晶合金的电子束焊接

近年来已能用较低的冷却速度 (1～ 10 0Ｋ/ｓ)直接由熔体制取厚度 10ｍｍ左右的高玻璃形成能力的大块非晶合金。这种大块非晶合金也具有在晶化前很宽的过冷液相区和高变形率超塑性以及在过冷液相状态优良的加工性。在 2 0 0 1年日本熊本大学解决了大块非晶合金材料的焊接问题 ,     

高强韧Ti-Ni基块体金属玻璃复合材料高温变形行为

采用水冷Cu坩埚悬浮熔炼-Cu模吸铸法制备了Ti-Ni基块体金属玻璃复合材料(BMGCs)试棒,研究了合金的微观组织、热力学行为以及室温和高温力学性能。结果表明,该铸态合金组织由非晶基体和过冷奥氏体及热致马氏体组成,且晶体相尺寸由表及里增大。在室温压应力加载时,合金表现出优异的综合力学性能,其屈服强度为1286 MPa,断裂强度为2256 MPa,且塑性应变为12.2%。在过冷液相区压应力加载时,合金在高的变形温度和低应变速率下,表现出近Newtonian流变特征,其最佳变形温度为T480℃且与过冷液相区(SLR)的交集部分。温度为560℃、应变速率为5×10-4s-1时,合金应力敏感指数m和能量耗散率y分别为0.81和0.895。     

试样尺寸对镁基块体金属玻璃压缩力学行为的影响

研究试样直径和高径比对3种镁基块体金属玻璃Mg65Cu25Gd10、Mg65Cu20Ni5Gd10和Mg75Ni10Gd10压缩变形行为的影响,探讨镁基块体金属玻璃断裂模式的转变机制。压缩应力—应变曲线和断口扫描电镜观察结果表明:镁基块体金属玻璃Mg65Cu25Gd10、Mg65Cu20Ni5Gd10和Mg75Ni10Gd10在压缩条件下可在3个不同的变形阶段发生断裂,第1个是弹性变形阶段,在此变形阶段金属玻璃都以解理方式断裂,无塑性;第2个变形阶段的断裂为解理和剪切混合方式断裂,金属玻璃具有一定的剪切塑性变形;第3个变形阶段为稳定剪切锯齿塑性流变阶段,在此变形阶段金属玻璃都是以剪切方式断裂,具有稳定的塑性变形;镁基块体金属玻璃的断裂模式与尺寸有关,减小试样的直径和高径比都有利于块体金属玻璃由解理断裂向剪切断裂的转变,强度和塑性也相应地得到提高。     

KINETIC STUDY ON FORMATION OF BULK GLASS STATE Zr52.5Ni14.6Al10Cu17.9Ti5 ALLOY

１ＩＮＴＲＯＤＵＣＴＩＯＮＭｏｓｔｍｅｔａｌｉｃａｌｏｙｓｕｓｕａｌｙｈａｖｅａｌｏｗｅｒｇｌａｓｔｒａｎｓｉｔｉｏｎｔｅｍｐｅｒａｔｕｒｅＴｇ,ｔｈｅｉｒｇｌａｓｓｔａｔｅａｒｅｆｏｒｍｅｄｉｎｔｈｅｃｏｎｄｉｔｉｏｎｏｆｆａｓｔｅｒｃｏｏｌｉｎｇ...     

Nd_(60)Al_(15)Cu_(10)Co_(10)Fe_5大块非晶态合金的制备

采用铜模浇铸法制得直径４．０ｍｍ、长６０ｍｍ圆柱状Ｎｄ６０Ａｌ１５Ｃｕ１０Ｃｏ１０Ｆｅ５大块非晶样品。样品的非晶性经Ｘ射线衍射（ＸＲＤ）实验检验证实。采用示差扫描热分析（ＤＳＣ）、Ｘ射线衍射分析了非晶合金的晶化过程。Ｎｄ６０Ａｌ１５Ｃｕ１０Ｃｏ１０Ｆｅ５非晶态合金的约化玻璃温度Ｔｒｇ＝０．６０,说明合金有较好的非晶形成能力。采用Ｋｉｓｓｉｎｇｅｒ方法求得非晶态合金的表观晶化激活能。根据熔化焓对Ｎｄ６０Ａｌ１５Ｃｕ１０Ｃｏ１０Ｆｅ５合金深过冷液相与稳定晶相间的吉布斯自由能差进行了估算。结果表明,Ｎｄ６０Ａｌ１５Ｃｕ１０Ｃｏ１０Ｆｅ５合金深过冷液相与稳定晶相间的吉布斯自由能差,ΔＧ,在过冷液相区小于２ｋＪ／ｍｏｌ,表明过冷液相的晶化驱动力很小,过冷液相区内的晶相形核具有较大的热垒。     

Structural transformation and rheological processes in bulk metallic glass Zr41Ti14Cu12.5 Ni10Be22.5

The temperature dependence of strain and strain rate of the Zr41Ti14Cu12.5Ni10Be22.5 (Vitl) bulk metallic glass (BMG) under constant heating condition was derived from the static extension method with a dynamic thermal mechanical analyzer (DMA). A few strain rate peaks, which corresponds to the glass transition and multistep crystallization in the differential scanning calorimeter (DSC) examination, were observed in the curves of the relation between strain rate and temperature. The onset of viscous flow and the end of glass transition are interrelated, the first and second strain rate peaks correspond with the first and second crystallization transition processes, respectively.The influence of stress on strain and strain rate was researched. It is found that the rheological behaviour of BMG Vitl changes from elasticity to anelasticity, finally to the Newtonian viscous flow along with increasing temperature.     

Effect of cold rolling on glass transition of Zr_(55)Al_(10)Ni_5Cu_(30) bulk metallic glass

Zr55Al10Ni5Cu30 bulk metallic glass was prepared through water-cooled copper mold suction casting, and was rolled up to 95% in thickness reduction. The structures and thermal stabilities of the as-cast and as-rolled specimens were examined by X-ray diffractometer and differential scanning calorimeter. As the thickness reduction increases, the crystallization onset temperature, peak temperature and the apparent activation energy of crystallization almost keep constant, while the glass transition temperature decreases from 681 to 671 K and the apparent activation energy of glass transition increases from (404±26) to (471±29) kJ/mol. The glass transition process is markedly affected by the rolling induced changes of microstructure and structural relaxation.     

Corrosion behaviour of the amorphous Mg65Y10Cu15Ag10 alloy

The corrosion behaviour of the amorphous Mg₆₅Y₁₀Cu₁₅Ag₁₀ alloy as well as of its crystalline multiphase counterpart was studied in alkaline electrolytes and compared with that of the amorphous Mg₆₅Y₁₀Cu₂₅ alloy. Electrochemical investigations were carried out in 0.3 M H₃BO₃/Na₂B₄O₇ buffer solution with pH=8.4 and in 0.1 M NaOH solution with pH=13. Tafel plots were recorded and cyclic potentiodynamic polarisation tests were conducted, transients were measured at anodic potentials. Potentiostatically formed surface layers were characterised by Auger electron spectroscopy and atomic force microscopy. Changes in the corrosion behaviour were noticed which are attributed to the presence of silver. The passive layers formed in the two electrolytes were quite different in the composition as well as in morphology. The layer growth mechanisms also showed some variation presumably mainly due to the presence of silver, though copper still seems to play a dominant role in the passivation of this alloy in the weakly alkaline solution. The amorphous alloys displayed superior corrosion behaviour compared to the crystalline alloy, because of the absence of the heterogeneties existing in crystalline alloys.     

Amorphous-crystalline transition layers formation during quenching of Fe61Co7Zr10Mo5W2B15melt

New Fe-based multicomponent amorphous alloys have been developed recently based on empirical rules for large glass forming ability(GFA).In the present investigation,the master alloy ingot with the nominal composition of Fe61Co7Zr10Mo5W2B15(mole fraction,%)was prepared by arc-melting under Ti-gettered Ar atmosphere. The Fe-based uttons with different transverse cross sections were fabricated by arc-melting method,and the d2.5mm Fe-based rods were manufactured by injection technique.Characterization of the ingots and the parameters associated with the thermal stability were carried out by X-ray diffractometry(XRD)and high temperature differential scanning calorimeter(DSC),respectively.The interval of the supercooled liquid region is 39K for the Fe-based alloy.The GFA of Fe-based alloys is relatively lower,to the buttons obtained are all crystallized.The Fe-based rod exhibites a high Vickers hardness up to HV 1329.In addition,and amorphous-crystalline transition layers are observed in the rod.This transition zone is caused by unhomogeneous temperature distribution and relatively lower GFA for Fe-based alloys.     

Calorimetric study of non-isothermal crystallization kinetics of Zr60Cu20Al10Ni10 bulk metallic glass

The non-isothermal differential scanning calorimetric techniques were used to evaluate the thermal stability and crystallization kinetics of Zr₆₀Cu₂₀Al₁₀Ni₁₀ bulk metallic glass. Various models were used to analyze the non-isothermal DSC at the heating rates (?) ranging from 1 to 80 K/min. The Kissinger equation, Ozawa equation, Augis-Bennett equation, Lasocka equation, and Vogel-Fulcher-Tammann non-linear equation were employed to describe the relationship between the crystallization peak temperatures and the heating rates. The overall crystallization activation energies of the metallic glass were estimated using the Kissinger, Ozawa and Augis-Bennett methods, respectively. The local activation energies at various volume fraction of crystalline phases were obtained by general Ozawa's isoconversional method. The crystallization kinetics was specified by a function reflecting crystallization mechanism. It has been found that a critical heating rate exists at around 20 K/min, beyond which the shapes of the DSC curves and the various relationships are varied. The crystallization process of the metallic glass can be divided into two groups, i.e. a slow heating rates region with ? = 1-20 K/min, and a rapid heating rates region with ? = 30-80 K/min. The overall crystallization activation energy for the slow heating rates regions is much larger than that for the rapid heating rates region. The crystallization activation energy derived from the Kissinger's peak temperatures is 326.4 ± 11.3 kJ/mol for the slow heating rates region, and 202.2 ± 26.6 kJ/mol for rapid heating rates region, respectively. The crystallization mechanisms were discussed with Johnson-Mehl-Avrami (JMA) and normal grain growth (NGG) mode. The crystallization mechanisms are different for the two heating rates regions. A transition point was found at the NGG-controlled crystallization stage for the higher heating rates, while it was absent for the slower heating rates.     

添加微量Fe对Zr_(55)Al_(10)Ni_5Cu_(30)块体金属玻璃非晶形成能力和力学性能的影响(英文)

通过磁悬浮熔炼和铜模吸铸法制备直径3mm的(Zr0.55Al0.10Ni0.05Cu0.30)100-xFex(x=0,1,2,3,4)合金试样,研究Fe元素的微量添加对Zr55Al10Ni5Cu30块体金属玻璃非晶形成能力和力学性能的影响。研究表明,合理添加Fe元素(不超过3%,摩尔分数)导致约化玻璃转变温度Trg(=Tg/Tl)和参数γ(=Tx/(Tg+Tl))增大,因而其非晶形成能力增大,但添加过量的Fe元素(4%)会导致其非晶形成能力的降低。添加Fe元素也会显著地改善Zr55Al10Ni5Cu30块体金属玻璃的压缩塑性及提高其压缩断裂强度,当Fe元素的添加量为2%时,直径3mm、长度6mm的试样在压缩时出现一定的塑性及加工硬化现象。Fe元素添加量为4%形成的金属玻璃基复合材料,同样也显示良好的压缩塑性和高的压缩断裂强度。     

块状非晶合金纳米压痕微区形变的研究

对Zr55A110Ni5Cu30块状非晶合金进行了室温纳米压痕实验，利用扫描电子显微镜、透射电子显微镜揭示了非晶合金的微区形变特征。结果表明：在压痕周围形成离散的剪切带，形变引起了块状非晶合金局部自由体积增加。利用自由体积模型对非晶合金的微区形变机制进行了分析。     

Glass transition kinetics of La55Al25Ni10Cu10 bulk metallic glass by electrical resistivity measurement

The glass transition behavior of La55A125-Ni10CU10 bulk metallic glass was investigated using elec-trical resistivity and differential-scanning calorimetry measurements. There are good agreements of the onset temperature （Tg-onset） and the end temperature （Tg-end） of the glass transition between the DSC curve and tempera-ture dependent electrical resistivity （TER） curve in the same heating rate. Kinetics of the glass transition is studied with the electrical resistivity data. The apparent activation energy of the glass transition （△Eg） is found to be 306.4 kJ.mol^-1. Fragility parameter D^＊ and VFT temper-ature To are 9.8 and 324.9 K, respectively.