近幾十年來，非晶質合金因具有一些獨特的物理性質及化學性質，因此引起世界各地眾多學者的研究與探討，隨著時代進步許多研究家的努力下，以往在非晶質合金製造尺寸限制的難題早已克服，其中塊狀非晶質合金為最近這幾年的研究主流，而在眾多非晶質合金系統中，鎂基非晶質合金因其具有高比強度，低玻璃轉換溫度和低密度等特性，因此在輕金屬之應用中，佔有相當大的發展潛力及優勢。

本實驗為鎂基塊狀非晶質合金之玻璃形成能力及機械性質之研究。Mg65Cu25Gd10合金經由傳統的銅模鑄造方式能夠成功的製作出具直徑3-6 mm及長度約5 cm的棒材，而藉由銀的添加後發現，Mg65Cu15Ag10Gd10合金亦可製作出相同尺寸大小的棒材。

在熱性質方面，Mg65Cu25Gd10非晶質合金顯示出寬廣的過冷液體區間，意味著其具有優良的熱穩定性，此外根據非晶質合金玻璃形成能力的參考指標，其結果顯示Mg65Cu25Gd10據有良好的玻璃形成能力，然而銀的添加會使得Mg65Cu15Ag10Gd10非晶質合金降低其熱穩定性及gama值，然而在Trg方面卻有著較高的值。在微氏硬度量測方面，Mg65Cu25Gd10非晶質合金顯示著非晶質高硬度之特性，再者銀添加的效應對於硬度來說更能有效增加其硬度。

The thermal and mechanical properties of the Mg-based bulk metallic glasses are reported in this thesis. The original ingots were prepared by arc melting and induction melting. The thermal and mechanical properties of the Mg-based bulk metallic glasses are reported in this thesis. The original ingots were prepared by arc melting and induction melting. The Mg65Cu25Gd10 and Mg65Cu15Ag10Gd10 bulk metallic glasses with different diameters from 3 to 6 mm were successfully fabricated by conventional copper mold casting in an inert atmosphere.

The Mg65Cu25Gd10 bulk metallic glass shows the high glass forming ability and good thermal stability. However, the addition of Ag in the Mg65Cu15Ag10Gd10 alloy degrades the thermal stability. Based on the DSC results, the supercooled liquid region

Content......................................................................................................................................... i
Tables List.................................................................................................................................. iv
Figures List.................................................................................................................................. v
Abstract……………………………………………………………………………………...... xi
1 Introduction……………………....................................................................................... 1
1.1 Amorphous metallic alloys….................................................................................. 1
1.2 The development of Mg-based amorphous alloys.................................................... 2
1.3 The effects of alloy additions in Mg-based alloys................................................... 3
1.4 The purpose of this study......................................................................................... 4
2 Background and literature review…................................................................................. 6
2.1 The evolution of amorphous alloys.......................................................................... 6
2.2 The evolution of fabrication methods of amorphous alloys.....................….…....... 8
2.3 The system of bulk amorphous alloys.................................................................... 10
2.4 The factors influencing the glass forming ability................................................... 11
2.5 The empirical rules for the synthesis of amorphous alloys.................................... 13
2.6 The characterization of amorphous alloys.............................................................. 16
2.6.1 Mechanical properties....................................................................................... 16
2.6.2 Magnetic properties………………………….................................................. 17
2.6.3 Chemical properties.......................................................................................... 18
2.6.4 Other properties of amorphous alloys.............................................................. 19
2.7 The deformation mechanisms of amorphous alloys……………………………... 20
3 Experimental procedures................................................................................................. 23
3.1 Materials................................................................................................................. 23
3.2 Sample preparation................................................................................................. 24
3.2.1 Arc melting.................................................................................................... 24
3.2.2 Induction melting........................................................................................... 25
3.2.3 Injection casting............................................................................................. 25
3.3 Property measurements and analyses..................................................................... 26
3.3.1 X-ray diffraction............................................................................................ 26
3.3.2 Qualitative and Quantitative constituent analysis......................................... 27
3.3.3 DSC thermal analysis.................................................................................... 27
3.3.4 Density measurements................................................................................... 27
3.3.5 Microhardness testing.................................................................................... 28
3.3.6 Compression testing...................................................................................... 28
3.3.7 Thermal mechanical and dynamic mechanical analyzer............................... 29
3.3.8 Microstructure examination........................................................................... 30
4 Results………………..………………............................................................................. 32
4.1 Sample preparations................................................................................................ 32
4.2 SEM/EDS observation........................................................................................... 33
4.3 XRD analyses……................................................................................................ 33
4.4 DSC analyses.......................................................................................................... 34
4.5 Density measurements…….................................................................................... 37
4.6 Microhardness tests……........................................................................................ 37
4.7 TMA/DMA analyses.............................................................................................. 38
4.7.1 TMA analysis................................................................................................. 38
4.7.2 DMA analysis............................................................................................... .39
4.8 Compression testing............................................................................................... 39
4.9 Compressive fracture characteristics...................................................................... 41
5 Discussions…………………............................................................................................ 44
5.1 The effects of the Ag addition on the Mg-Cu-Ag-Gd alloy system....................... 44
5.2 The glass forming ability of the Mg-Cu-Ag-Gd BMGs........................................ .45
5.3 Thermal mechanical properties of the Mg65Cu25Gd10 BMG................................... 48
5.3.1 TMA analysis................................................................................................. 48
5.3.2 DMA analysis............................................................................................... .49
5.4 Compressive mechanical properties of the Mg65Cu25Gd10 BMG with various specimen height to diameter ratios........................................................................ 51
6 Conclusions..……..…………………............................................................................... 56
References................................................................................................................................. 58
Tables......................................................................................................................................... 61
Figures....................................................................................................................................... 76

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