CAJ | 학술논문

研究热处理工艺对铸态Mg-4.2Zn-1.5RE-0.7Zr镁合金显微组织和力学性能的影响。结果表明：铸态Mg-4.2Zn-1.5RE-0.7Zr镁合金的显微组织主要由α-Mg、T相和Mg51Zn20相组成；单级等温时效(325°C，10 h)以及双级时效(325°C，4 h)+(175°C，14 h)处理均未能使T相和Mg51Zn20相溶入基体，且晶粒也未明显长大。在325°C下时效10 h，晶内析出大量短杆状β′1相，延长时效时间将导致β′1相粗化及数量减少。Mg-4.2Zn-1.5RE-0.7Zr镁合金在325°C下时效10 h后具有最高的屈服强度(153.9 MPa)和抗拉强度(247.0 MPa)，相比铸态合金分别增加48 MPa和23 MPa，伸长率降低至15.6%。Mg-4.2Zn-1.5RE-0.7Zr合金经双级时效(325°C，4 h)+(175°C，14 h)处理后的屈服强度和抗拉强度与单级等温时效处理(325°C，10 h)的相当，但伸长率有所下降。此外，不同状态下Mg-Zn-RE-Zr镁合金的断裂主要表现为准解理断裂，但局部特征有差别。
연구열처리공예대주태Mg-4.2Zn-1.5RE-0.7Zr미합금현미조직화역학성능적영향。결과표명：주태Mg-4.2Zn-1.5RE-0.7Zr미합금적현미조직주요유α-Mg、T상화Mg51Zn20상조성；단급등온시효(325°C，10 h)이급쌍급시효(325°C，4 h)+(175°C，14 h)처리균미능사T상화Mg51Zn20상용입기체，차정립야미명현장대。재325°C하시효10 h，정내석출대량단간상β′1상，연장시효시간장도치β′1상조화급수량감소。Mg-4.2Zn-1.5RE-0.7Zr미합금재325°C하시효10 h후구유최고적굴복강도(153.9 MPa)화항랍강도(247.0 MPa)，상비주태합금분별증가48 MPa화23 MPa，신장솔강저지15.6%。Mg-4.2Zn-1.5RE-0.7Zr합금경쌍급시효(325°C，4 h)+(175°C，14 h)처리후적굴복강도화항랍강도여단급등온시효처리(325°C，10 h)적상당，단신장솔유소하강。차외，불동상태하Mg-Zn-RE-Zr미합금적단렬주요표현위준해리단렬，단국부특정유차별。
The microstructures and mechanical properties of Mg-4.2Zn-1.5RE-0.7Zr alloy were investigated under different heat treatment conditions. The as-cast alloy consisted ofα-Mg phase, T-phase and Mg51Zn20 phase. After aging treatment (single-step (325 °C, 10 h) and two-step (325 °C, 4 h)+(175 °C, 14 h)), neither T-phase nor Mg51Zn20 phase dissolved into the matrix and the coarsening ofα-Mg phase was not significant. When peak-aged at 325 °C for 10 h, dense short rod-likeβ′1 phase precipitated in the matrix. Further ageing at 325 °C led to coarsening ofβ′1 phase and a decrease in number density. Alloy aged at 325 °C for 10 h achieved the highest yield strength (YS) and ultimate tensile strength (UTS) of 153.9 MPa and 247.0 MPa, which were increased by 48 MPa and 23 MPa from as-cast condition, respectively. While the elongation slightly decreased to 15.6%. Comparatively, the YS and UTS of alloy two-step aged by (325 °C, 4 h)+(175 °C, 14 h) showed little difference from those of single-step aged alloy, but with a lower elongation of 13.4%. In addition, the fracture surfaces of Mg-4.2Zn-1.5RE-0.7Zr alloy under different thermal conditions were mainly characterized by quasi-cleavage feature, but with differences in the details.