1at％ Ag替代Zr57Cu20Al10Ni8Ti5金属玻璃中各组元对玻璃形成能力及热稳定性的作用分析

以1at％ Ag元素分别等量替代Zr57Cu20Al10Ni8Ti5金属玻璃的各个组元,利用差示扫描量热升温分析获得不同试样的热力学参数,并结合不同尺寸(Φ8,Φ10,Φ12)吸铸试样的X-射线衍射分析结果,考察、验证元素替代后合金的实际玻璃形成能力及热稳定性的变化规律.经比较发现,Ag替代Ti元素,其玻璃形成能力显著提高(直径实际增大4 mm),同时热稳定性也明显改善,且临界冷却速率也明显降低,而Ag替代其他组元却无明显规律.针对玻璃形成能力的相关数据比较分析表明,本文结果未显示符合其Inoue的尺寸准则,混合焓判据也未显示出明显符合的现象.通过对堆垛密度的计算发现,1 at％ Ag替代Ti元素后使金属玻璃体系内部的堆垛密度增加.通过动力学分析,从晶化激活能、晶化反应速率常数两方面探讨了元素替代对玻璃形成能力和热稳定性的作用机理.

On glass forming ability and thermal stability of Zr57Cu20Al10Ni8Ti5 bulk metallic glass by substituting each component with 1 at% Ag

Each component element of Zr₅₇Cu₂₀Al₁₀Ni₈Ti₅ bulk metallic glass is substituted by 1 at% Ag element. Variations of glass forming ability and thermal-stability are studied using differential scanning calorimetry which gives the thermal-dynamic parameter of the bulk metallic glass, combined with X-ray diffraction of different diameter rods (Φ8, Φ10 and Φ12) which are prepared by copper mould suction casting, The results show that the glass forming ability and thermal-stability are greatly improved by substituting Ti element and the critical cooling rate is significantly reduced. While, no obvious law is found when substituting other elements. By analyzing the relevant data on glass forming ability, Inoue's atomic size rule show inconformity in this work, however, the mixing enthalpy rule dose not show conformity obviously. By calculating the packing density, we find that the packing density is obviously improved when substituting 1 at% Ti with Ag. Dynamic analysis is used and the mechanism of element substitution is also investigated on the aspects of crystallization activation energy and crystallization rate constant.