【作者】 梁红梅；

【导师】 马明臻；

【作者基本信息】 燕山大学 ， 材料学， 2006， 硕士

【摘要】 本文以Zr₅₅Al₁₀Ni₅Cu₃₀大块非晶合金作为研究对象,通过不同工艺条件下的退火,研究了非晶合金的非晶形成能力、晶化动力学和机械性能。利用X射线衍射分析了Zr₅₅Al₁₀Ni₅Cu₃₀非晶合金的结构及退火后非晶合金析出晶相的变化。首先析出的四方Al3Zr相,晶化结束后由稳定的四方Zr₂Cu和立方NiZr₂相组成。并且发现随着退火温度和退火时间的增加,析出的晶相越来越复杂,结晶度越来越大,晶粒尺寸也呈增长趋势。采用差示扫描量热分析对Zr₅₅Al₁₀Ni₅Cu₃₀大块非晶合金的晶化动力学进行了研究,并通过Kissinger法计算了不同退火条件下Zr₅₅Al₁₀Ni₅Cu₃₀大块非晶合金的晶化激活能。结果显示,随着退火温度和保温时间的改变,非晶合金的晶化激活能比淬态合金的均有提高趋势,说明退火后的非晶合金具有更好的热稳定性。对603K,0.5h、603K,5h、653K,0.5h、683K,2h这四个不同退火温度及时间得到的合金进行压缩试验,采用的位移速率为0.005mm/s。其压缩时的断裂强度和最大应变分别为1885MPa,7.5%、1721MPa,7.3%、1391MPa,10.0%、1292MPa,6.3%。其中退火条件为603K,0.5h的合金的断裂强度最大为1885MPa,比淬态合金的1242MPa提高了51.7%。由扫描电镜分析可知,低温退火后样品的断裂方式与淬态非晶合金的断裂方式相同,均为与外加压力轴呈约40°角的斜面上发生切变变形,断口呈脉状花样,最后的断裂形式为脆性断裂。晶化结束后的合金为粉碎性断裂,断口断裂方式没有规律。更多还原

【Abstract】 Zr₅₅Al₁₀Ni₅Cu₃₀ bulk amorphous alloy is chosen as the experimental alloy because of its strong amorphous forming ability and crystallization stability. The glass forming ability, crystallization kinetics and mechanical properties of Zr₅₅Al₁₀Ni₅Cu₃₀ bulk amorphous alloy has been investigated after annealed at different technological parameters.The structure of Zr₅₅Al₁₀Ni₅Cu₃₀ alloy and precipitated phases of annealed alloy was investigated by XRD. During the crystallization process, the tetragonal Al3Zr is firstly precipitated, then the stable tetragonal Zr₂Cu, cubic NiZr₂ were precipitated. With the increase of annealing temperature and annealing time, the precipitated phase is complicating and the crystallinity is increasing, the grain size of the precipitated phase is also increasing.The crystallization kinetics of Zr₅₅Al₁₀Ni₅Cu₃₀ bulk metallic glass was investigated by means of DSC under nonisothermal conditions. The effective activation energies for the crystallization of Zr₅₅Al₁₀Ni₅Cu₃₀ bulk metallic glasses were evaluated by Kissinger′s equation. The effective activation energies after annealing are higher than the as-quenched alloys’, which approved the annealed alloy have better thermal stability.The strain rate of the compressive experiment is 0.005mm/s. The fracture strength and strain of 603K, 0.5h、603K, 5h、653K, 0.5h and 683K, 2h are 1885MPa, 7.5%、1721MPa, 7.3%、1391MPa, 10.0% and 1292MPa, 6.3%. The fracture strength of 603K, 0.5h is the best and has an increase of 51.7 percent to the as-quenched alloy’s 1242MPa.The fracture mode of annealed alloy at low temperature is similar to the as-quenched alloys’, the sample fractures nearly along 40°direction of pressure axis and shear deformation occurred. The fracture morphology is veiny pattern and the fracture mode is brittle fracture. The fracture mode of completedcrystallization alloy is multiple cracking and the fracture morphology is irregular.更多还原