【作者】 吴冰；

【导师】 时海芳； 徐瑞；

【作者基本信息】 辽宁工程技术大学 ， 材料加工工程， 2008， 硕士

【摘要】 本文选取Al-2.8at%Ni-1.53at%Y三元合金,进行下拉式定向凝固实验,研究同一温度梯度下,不同拉伸速率对凝固组织的影响,以及定向凝固后合金的高温压缩性能。实验结果表明:Al-Ni-Y三元合金经定向凝固后或得了同一方向(热流反方向)的组织。随拉伸速率的增加,组织逐渐细化,初生相逐渐增多。定向凝固后的合金弹性极限提高了,且获得了对热加工有益的变形机制。高温压缩变形时的流变应力行为,可采用Zener-Hollomon参数的双曲正弦形式来描述;获得的流变应力σp解析表达式中α、n和A值分别为0.014Mpa-1、8.60和1.13×1022s-1;其热变形激活能Q为234.74kJ/mol。更多还原

【Abstract】 The drawing-directional solidification of the ternary Al alloy with composition of 2.8at%Ni, 1.53at%Y was carried out in this paper. We studied the effects of the same temperature gradient and different growth velocities on the solidified microstructure, and the comstress performance of the alloy in high temperatureThe experimental results shows that the microstructures of the directionally solidified alloy grow in the same direction . The microstructure of the directionally solidified alloy becomes finer and slender gradually and the more primaryα-Al is observed with the increasing of growth velocities. After directionally solidified, the elastic limit were improved. The useful deformation mechanism is observed in directionally solidified alloy. The flow stress of directionally solidified alloy during high temperature deformation can be represented by a Zener - Hollomon parameter in the hyperbolic Arrhenius– type equation.α、n and A in the analytical expressions ofσp are fitted to be 0.014Mpa-1、8.60 and 1.13×1022s-1 respectively. The hot deformation activation energy of directionally solidified alloy during high temperature deformation is 234.74kJ/mol.更多还原