【作者】 王艳；

【导师】 耿浩然；

【作者基本信息】 山东大学 ， 材料加工工程， 2009， 博士

【摘要】 非晶形成的机理以及热力学、动力学和结构对非晶形成能力的影响是材料科学的重要问题之一,目前也是非晶材料和物理领域研究的重点方向之一。非晶合金材料是由小于1nm的团簇密堆组成的,这种结构和其形成能力密切相关。微量元素掺杂（微合金化）技术在提高合金的玻璃形成能力（GFA）,增加非晶的机械/热力学稳定性和改善非晶磁性能和力学性能等方面发挥着有效和重要的作用,而且是探索新的非晶材料,改进非晶性能的有效方法。本文主要利用机械合金化（MA）法,以Zr基二元合金作为研究的基体合金,针对性的选择不同原子尺寸范围的单质元素、相近尺寸的不同元素、金属间化合物和异相非晶作为掺杂物,研究各掺杂物对MA诱导Zr-Ni基合金粉末显微结构演化行为的影响,进一步研究探讨元素或化合物掺杂对合金粉末的GFA和非晶机械/热力学稳定性的影响机理。另外,利用单辊旋转淬冷法,研究不同原子尺寸的元素掺杂对快速凝固Zr-Ni基合金显微结构演化和耐腐蚀性能的影响。综合研究元素掺杂效果与非晶制备技术的相关性。本课题从研究方向上为利用元素掺杂制备新的金属基非晶材料/复合材料和改善其腐蚀性能提供全面的实验与理论依据;从研究手段上扩展了非晶合金及其复合材料的制备方法,故而,对于开发新的非晶合金系统、优化合金成分具有重要的理论指导意义。本文以X射线衍射技术（XRD）、差示扫描量热分析（DSC）、扫描电子显微镜（SEM）、透射电子显微镜（TEM）和高分辨透射电子显微镜（HRTEM）、X射线能谱分析（EDX）为主要测试手段,主要研究内容和结论如下:利用MA法,在Zr_66.7Ni_33.3合金粉末中分别掺杂小原子尺寸的非金属元素C、中间原子尺寸Ag和大原子尺寸的稀土元素La取代基体元素Zr,不仅成功的制备了Zr_66.7-xNi_33.3C_x,Zr_66.7-xNi_33.3La_x和Zr_66.7-xNi_33.3Ag_x（x=0,1,3,5at.%）的单一非晶相,而且在相同球磨条件下,C,La和Ag的掺杂都显著的影响了MA诱导Zr-Ni合金粉末显微结构的演化行为。适量C的掺杂可明显缩短非晶反应开始时间,促进非晶化进程,提高合金粉末的GFA,而且还提高了非晶合金的机械稳定性;适量La的掺杂同样大大缩短了非晶反应开始时间,改善Zr-Ni合金粉末的GFA,而且1-5at.%La的掺杂可以显著的增强非晶相的机械稳定性,但是其机械稳定性随着La掺杂量的增加而降低;尽管Ag的掺杂并没有改善Zr-Ni合金粉末的GFA,但显著的延长了非晶粉末稳定存在的球磨时间,大大提高了非晶的机械稳定性。此外,延长球磨时间,单一的非晶相在球磨介质剪切力和碰撞力的作用下发生机械晶化,而且在特定元素掺杂量的条件下,Zr-Ni-C和Zr-Ni-La非晶相逐步向fcc-晶体相转变,而Zr-Ni-Ag非晶相向bc-晶体相转变。相同球磨条件下,综合比较具有显著原子半径区别的三种元素（C,La,Ag）的掺杂效果,1at.%La的掺杂对于提高Zr-Ni合金粉末的GFA和非晶机械稳定性两方面的综合影响效果最佳;C的掺杂在提高合金粉末GFA的影响效果优于Ag的掺杂,而在提高非晶稳定性方面,Ag的掺杂效果更好,因此,可知机械合金化合成Zr-Ni非晶相的机械稳定性随着掺杂元素原子半径的增大而提高。另外,从元素间混合热、原子错配度、球磨过程中的压力、原子团簇（键级）等方面,解释了不同原子尺寸元素掺杂对机械合金化Zr-Ni合金显微结构演化行为的影响。选用具有相近原子半径和化学性质的Pd,Ag和Au作为掺杂元素,研究在相同球磨条件下这些元素对MA诱导Zr-Ni合金显微结构演化行为的影响,分析探讨相近原子半径的元素掺杂对Zr-Ni合金GFA和机械/热稳定性不同影响效果的作用机理。微量掺杂Pd,Ag和Au（1at.%）并没有改善Zr-Ni合金粉末的GFA,但元素Au的微量掺杂可以明显的提高非晶合金的机械稳定性,而且Zr_65.7Ni_33.3Au₁非晶合金具有更高的热稳定性。根据与非晶合金XRD曲线上漫散主峰的峰位（2θ值）相对应的最近邻原子间距随球磨时间的变化,研究发现在整个MA过程中,Zr_65.7Ni_33.3Au₁非晶合金中自始至终发生着结构弛豫或原子重排等微观结构的变化。而对于Zr_66.7Ni_33.3,Zr_65.7Ni_33.3Pd₁和Zr_65.7Ni_33.3Ag₁非晶合金,其微观结构变化只发生在球磨初级阶段,而随着球磨时间的延长,局部区域的微观结构保持不变。因此认为,这三种非晶合金初始晶化阶段发生的是近邻原子间位置互换,而不改变互换原子相对距离的微观结构演化,在随后的晶化过程中再发生原子长程扩散来实现最后的有序原子排列构型。研究了中等原子尺寸Nb的掺杂对机械合金化Zr_66.7-xCu_33.3Nb_x（x=0,2,4at.%）合金粉末显微结构演化的影响。发现:在低转速（200rpm）的MA条件下,Nb的掺杂并没有促进Zr-Cu-Nb单一非晶相的形成,但其适量掺杂明显的加速了非晶化进程,缩短了非晶反应开始时间,从而提高了合金的GFA,而且,机械合金化Zr-Cu-Nb合金的GFA随着Nb含量的增加而提高;在高转速（350rpm）的MA条件下,可以获得单一的Zr-Cu-Nb非晶相,而且Nb元素的掺杂同样也加速了非晶化进程,缩短了非晶开始反应时间,机械合金化Zr-Cu-Nb非晶相的机械稳定性随着Nb含量的增加而提高,另外,延长球磨时间,Zr_66.7Cu_33.3非晶相发生机械晶化,逐步转变为fcc-Zr₂Cu晶体相。选用金属间化合物TiC作为增强颗粒,采用MA法诱导Zr-Ni基合金粉末发生固-固反应转变,分析研究TiC掺杂（1-5wt.%）对Zr-Ni合金粉末由晶态向非晶态转变过程中的结构演化行为及机械晶化行为的影响。采用适量的TiC掺杂,成功制备出以TiC为增强颗粒的非晶复合材料,而且,其适量掺杂明显的影响了Zr-Ni合金粉末显微结构的演化行为。根据EDX成分分析,TiC在Zr,Ni原子间的扩散不均匀,导致局域范围内原子无序度增大,从而改善非晶的形成能力和稳定性,其中5wt.%TiC的掺杂不仅缩短了非晶反应开始时间,提高了Zr-Ni合金粉末的GFA,而且大大增强了非晶复合材料的机械稳定性。DSC结果表明,3wt.%TiC掺杂导致非晶相的热稳定性优于5wt.%TiC的掺杂效果,说明MA合成Zr-Ni基非晶合金粉末的机械稳定性和其热稳定性之间无相关性。在MA条件下制备Zr_66.7Ni_33.3非晶作为基体相,通过掺杂与其成分不同的异相非晶合金Cu₅₀Ti₅₀,利用不同测试手段研究MA诱导混合非晶粉末的固-固转变机理,分析异相非晶对非晶复合相的形成能力、晶化行为和热稳定性的影响,进而探讨不同原子团簇间的交互作用关系及影响机制。适量异相非晶Cu₅₀Ti₅₀的掺杂能够显著影响Zr_66.7Ni_33.3非晶基体显微结构在MA过程中的演化行为,且两种不同类型原子团簇间的交互作用可以促使原子无序度增加或提高这种无序度的机械稳定性。其中,随着球磨时间的延长,3wt.%Cu₅₀Ti₅₀非晶掺杂可导致基体非晶相发生循环非晶化转变。此外,随着Cu₅₀Ti₅₀非晶掺杂量一定程度的增加,Cu,Ti原子扩散不均匀,Ti更易占据二十面体Zr₉Ni₄团簇中Ni的位置,增大了原子间的亲和力,从而使原子排列无序度增加,混合非晶粉末的机械稳定性提高;但在相同球磨时间条件下,混合非晶粉末的热稳定性随着异相非晶掺杂量的增加而降低。与MA制备非晶技术作对比,采用单辊旋转淬冷法,通过分别掺杂小原子尺寸Si,中等原子尺寸Pd和大原子尺寸La三种元素,研究Zr-Ni-M（M=Si,Pd或La）合金在快速凝固条件下非晶化的转变机理,并结合MA研究结果,系统地探讨不同原子半径的元素掺杂对Zr-Ni基合金的GFA、非晶热稳定性及非晶微观结构的影响机理。此外,利用浸泡实验方法对Zr-Ni-M非晶薄带进行抗腐蚀能力测试,研究不同元素掺杂效果和非晶耐蚀性的相关性。研究发现,大尺寸La的掺杂明显提高了Zr-Ni非晶合金的GFA。根据Miracle金属玻璃原子模型,Ni-La的R值可能最接近R_N^*值,导致团簇达到最有效的原子排列,从而表现出优良的影响效果,这和MA研究结果相似。元素Si,Pd和La的掺杂都可以提高Zr-Ni-M非晶合金的热稳定性。根据非晶合金的激活能计算结果,进一步证实了元素掺杂有助于提高Zr-Ni非晶合金的热稳定性,且随着掺杂量增加,非晶热稳定性也随之提高,其中3at.%Si的掺杂对非晶热稳定性的提高效果最佳。但是,不同元素掺杂引起的非晶热稳定性变化趋势并没有随着冷却速度的增加而发生变化。此外,非晶薄带的耐蚀性试验表明,中等原子尺寸Pd的掺杂大大降低Zr-Ni非晶薄带的耐蚀性,而La取代Zr或Ni原子可使Zr基非晶合金容易钝化,故适量La的掺杂（3at.%）能够显著提高Zr-Ni非晶薄带的耐蚀性。更多还原

【Abstract】 The influence of thermodynamics,kinetics and structure on the glass forming ability（GFA）,as well as formation mechanism of amorphous alloys,is one of important issues for materials science.At present,this is also one of key research directions in amorphous materials and physics.Amorphous alloys are composed of close-packed clusters with a size less than 1 nm,and this structure is closely associated with their forming ability.Minor addition（Microalloying） technique plays an effective and important role in increasing the GFA of alloys, enhancing the mechanical/thermal stability of the amorphous phase,and improving magnetic and mechanical properties of amorphous alloys.Moreover, Minor addition technique is an effective method to explore novel amorphous materials and improve their properties.In the present work,we used Zr-based binary alloys as base alloys and pertinently selected elements with different atomic size magnitude,different elements with close atomic sizes,intermetallic compound and outphase amorphous alloys as additions.Using the mechanical alloying（MA） method,we investigated the influence of different kinds of additions on the microstructural evolution behavior of MA induced Zr-Ni-based alloy powders,and further probed into the effect and mechanism of additions of elements or compounds on the GFA and mechanical/thermal stability of the amorphous alloys.In addition, we also studied the influence of elemental additions with different atomic sizes on the microstructural evolution and corrosion-resisting properties of rapidly solidified Zr-Ni-based amorphous alloys using the single-roller melt-spinning technique.The correlation between the effect of elemental additions and fabrication techniques of the amorphous alloys has also been investigated.From the viewpoint of research direction,the present study supplies general experimental and theoretical bases for the fabrication of metallic amorphous materials/composites making use of elemental additions and the improvement of their corrosion-resisting properties.This study also expands the fabrication methods for the amorphous alloys and their composites.Therefore,our work is very important for the exploration of new amorphous alloy systems and for the optimization of alloy compositions.We mainly used X-ray diffraction（XRD）, differential scanning calorimetry（DSC）,scanning electron microscopy（SEM）, transmission electron microscopy（TEM）,high resolution transmission electron microscopy（HRTEM） and energy dispersive X-ray analysis（EDX） in this work. The research contents and conclusions are described as follows.Using the MA method,the single amorphous phase of Zr_66.7-xNi_33.3C_x, Zr_66.7-xNi_33.3La_x and Zr_66.7-xNi_33.3Ag_x（x=0,1,3,5at.%） has been successfully fabricated through substitution of non-metallic C with small atomic size,Ag with intermediate atomic size and rare-earth element La with large atomic size for the base metal Zr in Zr-Ni.Under the same milling conditions,the additions of C,La and Ag has an obvious effect on the microstructural evolution behavior of Zr-Ni alloys.An amount of C additions can markedly shorten the starting time of the amorphization reaction,facilitate the amorphization process,increase the GFA of the alloys,and improve the mechanical stability of the amorphous alloys. Similarly,the La addition can greatly shorten the starting time of the amorphization reaction and improve the GFA of the Zr-Ni alloy powders. Furthermore,the addition of 1-5at.%La can obviously enhance the stability of the amorphous phase against the mechanical crystallization.With increasing La addition,however,the mechanical stability of the Zr-Ni amorphous powders decreases.The Ag addition cannot improve the GFA of Zr-Ni,but significantly extends the milling time for the stable existence of the amorphous powders and greatly improves the mechanical stability of the amorphous phase.In addition, the amorphous phase starts to mechanically crystallize with increasing milling time when subjected to shearing and collision forces of milling media.Moreover, the Zr-Ni-C and Zr-Ni-La amorphous phases gradually transform into an fcc-phase,but the Zr-Ni-Ag amorphous phase transforms into a bc-phase,with a certain amount of elemental additions.We comprehensively compare the addition effect of three elements（C,La,Ag） with quite different atomic radii under the same milling conditions.The addition of 1 at.%La shows an optimum effect on the improvement of the GFA and mechanical stability of the Zr-Ni amorphous alloys.The effect of the C addition is better than that of the Ag addition for the improvement of the GFA of Zr-Ni,but the effect of the Ag addition is better than that of the C addition for the improvement of mechanical stability of the amorphous phase.Therefore,the mechanical stability of the MA induced Zr-Ni amorphous phase increases with increasing atomic radius of the additional elements.In addition,the influence of elemental additions with different atomic sizes on the microstructural evolution behavior of mechanically alloyed Zr-Ni alloys has been discussed based upon heat of mixing between elements,mismatch of atoms,pressure produced during ball milling and atomic clusters（bond order）,and so forth.We selected Pd,Ag and Au with similar atomic radii and chemical properties as additional elements,and investigated the influence of these elements on the microstructural evolution behavior of MA induced Zr-Ni alloys under the same ball milling conditions.We also probed into the mechanism of effect of elemental additions with similar atomic radii on the GFA and mechanical/thermal stability of Zr-Ni alloys.The minor additions of Pd,Ag and Au（1 at.%） do not improve the GFA of Zr-Ni alloys,but the minor addition of Au can markedly increase the mechanical stability of the amorphous alloys. Furthermore,the Zr_65.7Ni_33.3Au₁ amorphous alloy has higher thermal stability. According to the variation（with increasing milling time） of nearest-neighbor atomic distance corresponding to the position of the first maximum peak（2θ） on the XRD patterns of the amorphous alloy,it has been found that the structural relaxation or atomic rearrangement of the Zr_65.7Ni_33.3Au₁ amorphous alloy always takes place during the entire MA process.For the Zr_66.7Ni_33.3, Zr_65.7Ni_33.3Pd₁ and Zr_65.7Ni_33.3Ag₁ amorphous alloys,however,the microstructural transition occurs only at the initial milling stage.The local microstructure of these amorphous alloys almost keeps invariable with further prolonged milling time.Therefore,it is reasonable to assume that the initial crystallization of these three amorphous alloys proceeds through the interchange of the sites of neighboring atoms,keeping the relative atomic distance of the involved atoms invariable.During the later crystallization process,the long-range diffusion of atoms occurs resulting in the ordered atomic configuration.The influence of Nb with intermediate atomic size on the microstructural evolution of mechanically alloyed Zr_66.7-xCu_33.3Nb_x（x=0,2,4at.%） alloys has been investigated.At the lower speed of 200 rpm,the Nb addition does not lead to the formation of a single amorphous phase,but an amount of Nb addition obviously accelerates the amorphization process and shortens the starting time of the amorphization reaction,indicating the improvement of GFA.Moreover,the GFA of mechanically alloyed Zr-Cu-Nb alloys increases with increasing Nb addition.At the higher speed of 350 rpm,a single Zr-Cu-Nb amorphous phase can be obtained.Furthermore,the Nb addition can also accelerate the amorphization process and shorten the starting time of the amorphization reaction.The mechanical stability of the Zr-Cu-Nb amorphous phase increases with increasing Nb content.In addition,the Zr_66.7Cu_33.3 amorphous phase mechanically crystallizes with increasing milling time,gradually transforming into the fcc-Zr₂CU phase.The intermetallic compound TiC was selected as enhanced particles,and the solid-solid reaction occurred during MA of Zr-Ni-based alloy powders.We investigated the influence of the TiC addition（1-5wt.%） on the microstructural evolution during the crystalline-amorphous transformation and on the mechanical crystallization behavior.The TiC enhanced amorphous composites have been successfully synthesized,and the TiC addition markedly affects the microstructural evolution behavior of Zr-Ni alloy powders.Based upon the EDX analysis,we have found that the diffusion of TiC among the atoms of Zr and Ni is inhomogeneous,leading to the increase of the disorder degree of atoms in local regions.Therefore,the TiC addition improves the GFA and stability of the Zr-Ni alloys.The addition of 5 wt.%TiC not only shortens the starting time of the amorphization reaction,but also improves the GFA of Zr-Ni alloy powders and greatly enhances the mechanical stability of the amorphous composites.The DSC results demonstrate that the effect of the addition of 3 wt.%TiC is better than that of the addition of 5 wt.%TiC on the improvement of thermal stability of the amorphous phase,suggesting that there is no correlation between thermal stability and mechanical stability of MA induced Zr-Ni-based amorphous alloys.We used MA-synthesized Zr_66.7Ni_33.3 amorphous phase as the base alloy and outphase Cu₅₀Ti₅₀ amorphous phase with different composition as the addition. The MA induced solid-solid transition mechanism of mixing amorphous powders has been studied using different testing instruments.We probed into the influence of the addition of the outphase amorphous phase on the forming ability, crystallization behavior and thermal stability of the mixing amorphous powders, and further discussed the interaction relationship of different atomic clusters and the effect mechanism.The addition of the outphase Cu₅₀Ti₅₀ amorphous phase can markedly influence the microstructural evolution behavior of the Zr_66.7Ni_33.3 amorphous alloy.Moreover,the interaction between two kinds of atomic clusters with different types can increase the disorder degree of atoms or improve the mechanical stability of the disorder.The addition of 3 wt.%Cu₅₀Ti₅₀ amorphous alloy can give rise to the cyclic amorphization transformation with increasing milling time.In addition,the diffusion of Cu and Ti atoms is inhomogeneous with increasing Cu₅₀Ti₅₀ addition,resulting in the occupation of Ni sites by Ti in the icosahedral Zr₉Ni₄ cluster and the increase of interatomic affinity.Therefore, the disorder of atoms increases and the mechanical stability of the mixing amorphous powders can be improved.Under the same milling conditions, however,the thermal stability of the mixing amorphous powders decreases with increasing addition of the outphase amorphous alloy.In comparion to the MA method,we investigated the amorphization mechanism of Zr-Ni-M（M=Si,Pd or La） with the additions of Si with small atomic size,Pd with intermediate atomic size and La with large atomic size under rapid solidification conditions,using the single-roller melt-spinning technique.In combination with the MA results,we systematically discussed the influence of elemental additions with different atomic radii on the GFA,thermal stability and microstructure of Zr-Ni-based alloys.In addition,the corrosion-resisting experiments were carried out to study the correlation between the addition effect of different elements and the corrosion-resisting properties of the amorphous alloys,using the emerging method.It has been found that the addition of La with large atomic size can markedly improve the GFA of Zr-Ni amorphous alloys.In terms of atomic model for metallic glasses proposed by Miracle,the R value of Ni-La is possibly closest to the R_N^* value,leading to the most effective arrangement of atoms in clusters.This explains the good effect of the La addition,similar to the MA results.The additions of Si,Pd and La can improve the thermal stability of Zr-Ni-M amorphous alloys,and this has been further confirmed by the evaluation of activation energy of the amorphous alloys. Moreover,the thermal stability of the amorphous alloys increases with increasing addition,and the addition of 3 at.%Si exhibits the optimum effect on the improvement of the thermal stability of the amorphous phase.However,the variation tendency of thermal stability of the amorphous phase does not change with increasing cooling rate.Additionally,the corrosion-resisting experiments show that the addition of Pd with intermediate atomic size greatly decreases the corrosion-resisting properties of the amorphous ribbons.The substitution of La for Zr or Ni may lead to the passivation of Zr-based amorphous alloys.Therefore, the addition of La（3at.%） can markedly improve the corrosion-resisting properties of Zr-Ni amorphous ribbons.更多还原