Zr-Ti-Ni-Be准晶的制备及其性能研究

发布时间：2018-04-05 01:03

  本文选题：块体准晶合金　切入点：合金化　出处：《燕山大学》2015年硕士论文

【摘要】：本文研究了Be元素的添加对单相稳定准晶Zr40Ti40Ni20合金的准晶形成能力,热力学稳定性以及力学性能的影响,利用非自耗电弧炉熔炼与铜模吸铸技术,成功制备出了(Zr40Ti40Ni20)100-xBex块体准晶合金。利用X射线衍射技术(XRD)分析了准晶合金的结构、利用差热扫描量热仪(DSC)测试了准晶合金的热力学特征参数及其热稳定性参数(准晶相转变为其它晶相的激活能),同时结合退火实验研究了准晶的相转变特征,用透射电子显微镜(TEM)观察并确定了准晶合金的微观结构。利用数显显微硬度计、万能材料试验机、扫描电子显微镜(SEM)等测试技术,研究了(Zr40Ti40Ni20)100-xBex块体准晶合金的显微硬度、室温压缩性能和压缩断口微观形貌特征。实验结果表明,适量Be的添加使得原准晶Zr40Ti40Ni20能够在一个相当宽的成分范围内(Zr40Ti40Ni20)100-xBex(0≤x≤16)获得纯准晶相。而已报到的纯准晶一般只在很窄的组分范围内形成。进一步研究发现,当添加16 at%的Be元素能够使准晶形成体系的临界尺寸由3 mm增加到10 mm(该尺度是采用相同方法制备的最大准晶尺度之一),这表明Be的添加显著提高了体系的准晶形成能力。XRD结果显示准晶衍射峰的晶面间距随Be含量的增加呈现出单调递减的趋势,通过分析认为Be原子在准晶中部分替代了Ni原子的位置,从而使得体系的短程堆垛更加紧凑,从而导致晶面间距降低。通过热力学分析发现Be的添加使准晶体系的热稳定性降低,(Zr40Ti40Ni20)88Be12和(Zr40Ti40Ni20)84Be16准晶在693 K处发生固固相变,由准晶相向更加稳定的晶体相转变。块体准晶合金(Zr40Ti40Ni20)100-xBex随着Be含量的增加,力学性能显著提高,主要体现在维氏硬度和断裂强度显著提高,同时韧性也有一定的改善。其中维氏硬度可达628,与未添加前比提高了21%;其断裂强度达到了1360 MPa,是原准晶的2.5倍,显示出了较好的力学性能。但是添加Be后准晶的断裂过程中不存在塑性变形阶段,仍为脆性断裂。
[Abstract]:In this paper, the effects of the addition of be elements on the formation ability, thermodynamic stability and mechanical properties of single-phase stable quasicrystalline Zr40Ti40Ni20 alloy have been studied. By means of non-consumable arc furnace melting and copper die suction casting technology, the bulk Zr40Ti40Ni20100-xBex quasicrystal alloy has been successfully prepared.The structure of quasicrystalline alloy was analyzed by X-ray diffraction technique.The thermodynamic and thermal stability parameters of quasicrystalline alloy were measured by differential scanning calorimeter (DSC). The activation energy of quasicrystalline phase was transformed into other crystalline phases, and the phase transition characteristics of quasicrystalline were studied by means of annealing experiment.The microstructure of quasicrystal alloy was observed and determined by TEM.By means of digital display microhardness tester, universal material tester and scanning electron microscope (SEM), the microhardness, compression properties and fracture morphology of bulk quasicrystal alloy Zr40Ti40Ni20- 100-xBex have been studied.The experimental results show that the pure quasicrystalline phase can be obtained by adding proper amount of be to the original quasicrystalline Zr40Ti40Ni20 in a wide range of compositions: Zr40Ti40Ni20100-xBext0 鈮，

本文编号：1712484