【摘要】 采用末端淬火方法和硬度测试研究Zn与Mg质量比m(Zn)/m(Mg)对Al-(3.0~5.0)Zn-(3.5~4.5)Mg-1.0Cu(质量分数)合金淬火敏感性的影响。基于透射电子显微镜微观组织观察结果,根据Zn和Mg原子与空位的相互作用就m(Zn)/m(Mg)对淬火敏感性的影响机理进行分析和讨论。研究结果表明:m(Zn)/m(Mg)增大会降低合金的淬火敏感性,m(Zn)/m(Mg)为0.7,1.13和1.36的合金末端淬火试样的淬透深度依次增加,分别为35,65和100 mm。m(Zn)/m(Mg)增大有利于慢冷试样时效时η′沉淀强化相的均匀形核,得到数量多、细小弥散的η′沉淀强化相,提高强化效果,降低因冷却速率减小而导致的硬度下降的程度,降低淬火敏感性。更多还原

【Abstract】 The effects of m(Zn)/m(Mg) on quench sensitivity of Al-(3.0-5.0)Zn-(3.5-4.5)Mg-1.0Cu(mass fraction) were investigated by end quenching technique and hardness testing. According to the microstructure examination by the transmission electron microscopy, the mechanism of m(Zn)/m(Mg) on quench sensitivity was discussed based on the interaction between Zn, Mg atoms and vacancies. The results show that the increase of m(Zn)/m(Mg) tends to decrease quench sensitivity. The hardened depths of the end-quenched and aged specimens of the alloys with m(Zn)/m(Mg) of 0.70,1.13 and 1.36 increase and the values are 35, 65 and 100 mm, respectively. The increase of m(Zn)/m(Mg) is favorable for homogeneous nucleation of η′ phase, and therefore leads to more and fine dispersed η′ hardening precipitates in the slowly-quenched specimens after aging. And the strengthening effect is enhanced, the drop degree of hardness due to slow quenching is decreased, and consequently quench sensitivity is lowered.更多还原