变质与微分热分析

Modification and Differential Thermal Analysis

用微机辅助微分热分析法,记录并分析了由不同变质剂处理的Al-Si合金熔体的冷却曲线及其微分曲线,并确定了变质效果与冷却曲线上某些特征值之间的关系。所用变质剂包括:混合稀土、纯锑、稀土/锑复合变质剂以及三元钠盐。热分析曲线的特征值定义在初生相析出阶段(Tu_1、t_1、T_L、t_2)和共晶转变期(Tu_2、t_3、T_E、ΔT_1等)。这些特征值的确定是通过数据采集和数据处理系统由微机自动完成的。把各种变质剂对这些特征值的影响与试件微观组织的变化有机的联系起来进行评价,研究了各种变质剂的作用机理。

The differential thermal analysis technique aided by microcomputer is used to record and analyze cooling curves and differential curves of Al-Si alloy melts modified with various modifying agents and the relationshipbetween the effect of modification and certain features of the curves has been established. The modifiers include: mischmetal, antimony, RE/Sb combination and trinary sodium salt. Caracteristics of the thermal analysis curves have been defined at the liquids transformation (Tu_1, t_1, T_L, t_2) and the binary Al-Si eutectic plateau (Tu_2, t_3, T_E, ΔT). The determination of these characteristics is automatically performed based on data acquisition and treatment system by a microcomputer. The influence of each modifier on the characteristics has been related to the evolution of the microstructures and the mechanism of modification has also been studied.