γ-TiAl基合金由于密度低,具有較高的強(qiáng)度和抗蠕變性能而成為重要的高溫材料,然其較低的延展性和抗氧化能力限制了其應(yīng)用和發(fā)展。選區(qū)激光熔化（Selective laser melting,SLM）技術(shù)是一種常用的增材制造技術(shù),該技術(shù)不需要特殊的加工工具和鑄模,在3D模型的基礎(chǔ)上通過(guò)逐層堆積來(lái)實(shí)現(xiàn)小批量和復(fù)雜結(jié)構(gòu)零件的加工,特別適用于難變形材料的加工。近年來(lái),人們研究了激光選區(qū)熔化制備γ-TiAl基合金的組織和性能,發(fā)現(xiàn)由于較快的冷卻速度,合金具有更細(xì)小的內(nèi)部組織,同時(shí)合金強(qiáng)度也得以提高。B,V,Y,Mo,和Cr等合金化元素的添加也在一定程度提高了合金的延展性和抗氧化性但和理想效果仍有差距。因此,為了進(jìn)一步提高γ-TiAl基合金的延展性和高溫抗氧化性,本研究將Nb元素添加入該合金并采用電磁攪拌輔助激光選區(qū)熔化技術(shù)來(lái)加工不容成分的合金。本研究中,通過(guò)激光選區(qū)熔化技術(shù)（SLM）在TC4合金基板上加工了不同Nb含量的Ti-Al-Mn-Nb合金,分析了不同Nb添加量合金的組織和性能。結(jié)果顯示:合金組織主要由四方點(diǎn)陣結(jié)構(gòu)的γ-TiAl相和密排六方點(diǎn)陣結(jié)構(gòu)的α₂-Ti_... 

【文章來(lái)源】：大連理工大學(xué)遼寧省 211工程院校 985工程院校 教育部直屬院校

【文章頁(yè)數(shù)】：74 頁(yè)

【學(xué)位級(jí)別】：碩士

【文章目錄】：
摘要
Abstract
1. Introduction
    1.1 Applications of γ-Ti Al based alloys
        1.1.1 Aerospace applications
        1.1.2 Automotive sectors
    1.2 Intermetallics
    1.3 Ti and its properties
    1.4 Al and it's properties
    1.5 Nb and its properties
    1.6 Titanium aluminde
        1.6.1 Intermetallic compounds
        1.6.2 Microstructure of γ-Ti Al
    1.7 Processing methods of γ-Ti Al
        1.7.1 Additive manufacturing
        1.7.2 Selective laser Melting
    1.8 Residual stresses
    1.9 Effect of electromagnetic stirring
        1.9.1 Rotating electromagnetic stirring
        1.9.2 Linear electromagnetic stirring
        1.9.3 Pulsed magnetic field
2. Experimental materials and methods
    2.1 Materials
    2.2 Selective laser melting (SLM)
    2.3 Material characterizations
        2.3.1 X-ray diffraction (XRD)
        2.3.2 Scanning electron microscope (SEM)
    2.4 Mechanical test procedures
        2.4.1 Microhardness
        2.4.2 Compression test
    2.5 Tribological test procedures
    2.6 High temperature oxidation-resistance
    2.7 Rotating electromagnetic stirring
3. Results and discussions
    3.1 The effect of Nb on microstructure of γ-Ti Al
        3.1.1 Phase identification
        3.1.2 Phase morphologies
    3.2 The effect of Nb on mechanical properties of γ-Ti Al
        3.2.1 Microhardness
        3.2.2 Compressive analysis
    3.3 The effect of Nb on tribological properties of γ-Ti Al
    3.4 The effect of Nb on high temperature oxidation resistance of γ-Ti Al
4. Crack and holes analysis
    4.1 Crack formation
    4.2 Holes formation
5. Results and discussions
    5.1 The effect of EMS on microstructure and microhardness of γ-Ti Al
        5.1.1 Phase identification
        5.1.2 Phase morphologies
        5.1.3 Microhardness
Conclusions
References
Appendix A
Research Projects and Publications in Master Study
Acknowledgement



本文編號(hào)：3462445