CAJ | 학술논문

采用不同的固溶处理工艺对冷室压铸法制备的 Mg-9Al-1Zn-0.2Mn(质量分数)合金进行热处理，随后在150℃/5 h条件下进行时效处理，通过X射线衍射、金相显微镜与扫描电镜观察及硬度测试，研究固溶处理工艺与时效对合金显微组织与硬度的影响。结果表明，固溶处理可使压铸态合金晶界处的β-Mg17Al12相充分分解并溶入到α-Mg基体中。提高固溶温度和延长固溶时间，均可减少以连续网状形态分布于α-Mg枝晶间的β-Mg17Al12硬脆相，使其由晶间析出转变为α-Mg晶内析出。但固溶温度过高或固溶时间过长都导致α-Mg基体组织粗化，并发生过烧现象。固溶处理后的时效过程中，β-Mg17Al12相从过饱和固溶体中以不连续和连续2种方式析出，从而提高合金的硬度。
채용불동적고용처리공예대랭실압주법제비적 Mg-9Al-1Zn-0.2Mn(질량분수)합금진행열처리，수후재150℃/5 h조건하진행시효처리，통과X사선연사、금상현미경여소묘전경관찰급경도측시，연구고용처리공예여시효대합금현미조직여경도적영향。결과표명，고용처리가사압주태합금정계처적β-Mg17Al12상충분분해병용입도α-Mg기체중。제고고용온도화연장고용시간，균가감소이련속망상형태분포우α-Mg지정간적β-Mg17Al12경취상，사기유정간석출전변위α-Mg정내석출。단고용온도과고혹고용시간과장도도치α-Mg기체조직조화，병발생과소현상。고용처리후적시효과정중，β-Mg17Al12상종과포화고용체중이불련속화련속2충방식석출，종이제고합금적경도。
Mg-9Al-1Zn-0.2Mn alloy (mass fraction, %) prepared by cold chamber die casting was heat treated by different solution treatment technologies and then aged at 150 ℃/5 h. The effect of solution treatment on the microstructure and hardness of the die-casting alloys was investigated using X-ray diffraction, optical microscope, scanning electron microscopy and Vickers hardness testing. The results show that theβ-Mg17Al12 phases distributed along the grain boundary can dissolve intoα-Mg matrix through the solid-solution treatment.With increasing temperature and time of solid-solution treatment,theβ-Mg17Al12 phase existed continuously as netlike in the grain boundaries ofα-Mg phase decreases and precipitates at the inner ofα-Mg crystal instead of in grain boundaries. However, the crystal grain of die-casting alloy will be coarsed and over sintering if the solution temperature is too high or the solution time is too long. The aging treatment after solid-solution treatment make β-Mg17Al12 phases occur with discontinuous and continuous precipitation from oversaturatedα-Mg solid solution, and thus increase the hardness of the die-casting alloys.