本文選題：塊體準晶合金　切入點：合金化　出處：《燕山大學(xué)》2015年碩士論文

【摘要】：本文研究了Be元素的添加對單相穩(wěn)定準晶Zr40Ti40Ni20合金的準晶形成能力,熱力學(xué)穩(wěn)定性以及力學(xué)性能的影響,利用非自耗電弧爐熔煉與銅模吸鑄技術(shù),成功制備出了(Zr40Ti40Ni20)100-xBex塊體準晶合金。利用X射線衍射技術(shù)(XRD)分析了準晶合金的結(jié)構(gòu)、利用差熱掃描量熱儀(DSC)測試了準晶合金的熱力學(xué)特征參數(shù)及其熱穩(wěn)定性參數(shù)(準晶相轉(zhuǎn)變?yōu)槠渌嗟募せ钅?,同時結(jié)合退火實驗研究了準晶的相轉(zhuǎn)變特征,用透射電子顯微鏡(TEM)觀察并確定了準晶合金的微觀結(jié)構(gòu)。利用數(shù)顯顯微硬度計、萬能材料試驗機、掃描電子顯微鏡(SEM)等測試技術(shù),研究了(Zr40Ti40Ni20)100-xBex塊體準晶合金的顯微硬度、室溫壓縮性能和壓縮斷口微觀形貌特征。實驗結(jié)果表明,適量Be的添加使得原準晶Zr40Ti40Ni20能夠在一個相當(dāng)寬的成分范圍內(nèi)(Zr40Ti40Ni20)100-xBex(0≤x≤16)獲得純準晶相。而已報到的純準晶一般只在很窄的組分范圍內(nèi)形成。進一步研究發(fā)現(xiàn),當(dāng)添加16 at%的Be元素能夠使準晶形成體系的臨界尺寸由3 mm增加到10 mm(該尺度是采用相同方法制備的最大準晶尺度之一),這表明Be的添加顯著提高了體系的準晶形成能力。XRD結(jié)果顯示準晶衍射峰的晶面間距隨Be含量的增加呈現(xiàn)出單調(diào)遞減的趨勢,通過分析認為Be原子在準晶中部分替代了Ni原子的位置,從而使得體系的短程堆垛更加緊湊,從而導(dǎo)致晶面間距降低。通過熱力學(xué)分析發(fā)現(xiàn)Be的添加使準晶體系的熱穩(wěn)定性降低,(Zr40Ti40Ni20)88Be12和(Zr40Ti40Ni20)84Be16準晶在693 K處發(fā)生固固相變,由準晶相向更加穩(wěn)定的晶體相轉(zhuǎn)變。塊體準晶合金(Zr40Ti40Ni20)100-xBex隨著Be含量的增加,力學(xué)性能顯著提高,主要體現(xiàn)在維氏硬度和斷裂強度顯著提高,同時韌性也有一定的改善。其中維氏硬度可達628,與未添加前比提高了21%;其斷裂強度達到了1360 MPa,是原準晶的2.5倍,顯示出了較好的力學(xué)性能。但是添加Be后準晶的斷裂過程中不存在塑性變形階段,仍為脆性斷裂。
[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，

本文編號：1712484