中文摘要：

采用计算机辅助冷却曲线分析技术研究砂型铸造过程中冷却速率(1.4~3.5°C/s)对Mg-10Gd-3Y-0.4Zr合金凝固行为的影响。结果表明:随着冷却速率的提高,起始形核温度(Tα,N)由634.8°C升至636.3°C,再辉前最低温度(Tα,Min)由631.9°C降至630.7°C,形核过冷度(ΔTN)由2.9°C升至5.6°C,共晶反应起始温度(Teut,N)上升,固相线温度(T S)由546.0°C降至541.4°C,凝固温度区间(ΔTS)增加6.1°C。形核速率(N)的增加引起晶核数量的增加,从而降低α-Mg的平均晶粒粒径。相对于形核时间(ΔtN),形核过冷度(ΔTN)对α-Mg平均晶粒粒径的影响更大。温度增加值(T eut,N-T eut,G)与缩短的反应时间改变共晶反应进程,并且影响第二相的含量以及形貌。

英文摘要：

The effect of the cooling rate ranging from 1.4 °C/s to 3.5 °C/s on the solidification behavior of the sand-cast Mg?10Gd?3Y?0.4Zr alloy was studied by computer aided cooling curve analysis (CA-CCA). With the increase in cooling rate, the nucleation temperature (Tα,N) increases from 634.8 °C to 636.3 °C, the minimum temperature (Tα,Min) decreases from 631.9 °C to 630.7 °C, the nucleation undercooling (ΔTN) increases from 2.9 °C to 5.6 °C, the beginning temperature of the eutectic reaction (Teut,N) increases, the time of the eutectic reaction shortens, solidus temperature decreases from 546.0 °C to 541.4 °C, and solidification temperature range (ΔTS) increases by 6.1 °C. The increased nucleation rate (N&) is supposed to be the main reason for the increased?TN. Increased value (Teut,N?Teut,G) and shortened time of the eutectic reaction cause the change in the volume fraction and morphology of the second phase.