CAJ | 학술논문

通过Clyne-Davies模型对MgZn2.5YxZr0.5(x=0.5,1,2,4,6)系合金的热裂敏感性进行预测；采用X射线衍射和扫描电子显微镜分别对MgZn2.5YxZr0.5系合金进行显微组织和热裂区域组织形貌观察，并用自制的“T”形热裂模具，通过A/D转换，用计算机对MgZn2.5YxZr0.5系合金凝固过程中的温度、收缩应力信号数据进行采集和进一步的处理，并描绘其曲线。研究 MgZn2.5YxZr0.5合金的凝固温度区间、脆弱区域的凝固温度变化、凝固最后阶段剩余液相分数以及合金中第二相种类等因素对 MgZn2.5YxZr0.5系合金热裂倾向的影响：合金热裂倾向从大到小顺序为 MgZn2.5Y2Zr0.5，MgZn2.5Y0.5Zr0.5，MgZn2.5Y4Zr0.5，MgZn2.5Y6Zr0.5，MgZn2.5Y1Zr0.5。由于 MgZn2.5Y2Zr0.5合金的凝固温度区间最宽，脆弱区域的凝固温度变化最大，凝固最后阶段形成的液膜最少，枝晶干涉点后析出的第二相阻碍枝晶间的补缩等多种原因而造成合金的热裂倾向最大。
통과Clyne-Davies모형대MgZn2.5YxZr0.5(x=0.5,1,2,4,6)계합금적열렬민감성진행예측；채용X사선연사화소묘전자현미경분별대MgZn2.5YxZr0.5계합금진행현미조직화열렬구역조직형모관찰，병용자제적“T”형열렬모구，통과A/D전환，용계산궤대MgZn2.5YxZr0.5계합금응고과정중적온도、수축응력신호수거진행채집화진일보적처리，병묘회기곡선。연구 MgZn2.5YxZr0.5합금적응고온도구간、취약구역적응고온도변화、응고최후계단잉여액상분수이급합금중제이상충류등인소대 MgZn2.5YxZr0.5계합금열렬경향적영향：합금열렬경향종대도소순서위 MgZn2.5Y2Zr0.5，MgZn2.5Y0.5Zr0.5，MgZn2.5Y4Zr0.5，MgZn2.5Y6Zr0.5，MgZn2.5Y1Zr0.5。유우 MgZn2.5Y2Zr0.5합금적응고온도구간최관，취약구역적응고온도변화최대，응고최후계단형성적액막최소，지정간섭점후석출적제이상조애지정간적보축등다충원인이조성합금적열렬경향최대。
The hot tearing susceptibility of MgZn2.5YxZr0.5 (x=0.5, 1, 2, 4, 6) alloys was evaluated by thermodynamic calculations based on Clyne-Davies model. The microstructure and morphology of hot tearing regions of the alloys were observed by X-ray diffraction and scanning electron microscopy. The solidification temperature and shrinkage stress during the solidification of MgZn2.5YxZr0.5 alloys in the“T”type hot tearing permanent-mold were acquired with the attached computer. The effect factors of hot tearing susceptibility of MgZn2.5YxZr0.5 alloys, such as the solidification temperature interval, the variation of solid fraction in vulnerable region, the residual liquid fraction in the final stage, the type of the second phase of the alloys were discussed based on the above calculation and observation. The results demonstrated that the hot tearing susceptibility in the investigated alloys was found as follows:MgZn2.5Y2Zr0.5>MgZn2.5Y0.5Zr0.5>MgZn2.5Y4Zr0.5>MgZn2.5Y6Zr0.5>MgZn2.5Y1Zr0.5. The highest hot tearing susceptibility of MgZn2.5Y2Zr0.5 alloy related to the following reasons: the largest freezing range, the biggest changing of the variation of solid fraction in vulnerable region, the least liquid film in the final stage of solidification, the formation of the second phase which worsens the liquid flow and interdendritic feeding after dendrite coherency.