Zr对Al-Zn-Mg-Cu合金动态软化行为的影响  

Effect of Zr on the Dynamic Softening Mechanism of Al-Zn-Mg-Cu Aluminum Alloy

作　　者：李隽莹 曹晓武[1] 杨继东[1] 徐国富[1] 

机构地区：[1]中南大学材料科学与工程学院

出　　处：《特种铸造及有色合金》2014年第9期976-979,共4页Special Casting & Nonferrous Alloys

基　　金：国家民口配套项目(JPPT-115-2-948)

摘　　要：在Gleeble-1500热模拟试验机上,对添加Zr元素的Al-Zn-Mg-Cu合金在300~450℃和0.000 5~1.000s-1变形下进行热压缩试验。采用金相显微观察（OM）、电子背散射衍射分析（EBSD）和透射电镜分析（TEM）测试技术,研究了不同热变形工艺下合金的显微组织演变规律。结果表明,随着变形温度的升高和应变速率的降低,合金的位错密度降低,亚晶尺寸增加,峰值应力减小。在热变形工艺条件下,合金组织主要由小角度晶界构成,动态软化机制主要为动态回复。在AlZn-Mg-Cu合金中添加Zr元素,生成了大量尺寸为10~25nm的弥散共格Al3Zr粒子,该粒子在热变形过程中有效钉扎位错和亚晶界,抑制热变形过程中再结晶的发生,是热变形条件下仍保持动态回复组织的原因。Hot compression test of the Al-Zn-Mg-Cu alloy with Zr addition was carried out on the Gleeble-1500 thermal simulation machine at 300~450℃and the strain rates of 0.000 5~1.000s-1.The microstructure of the alloy under different deformation conditions was observed using optical microscopy（OM）,electron back scattered diffraction（EBSD）and transmission electron microscopy（TEM）.The results show that the dislocation density is decreased and the subgrain size is increased with increasing in deformation temperatures or decreasing in strain rates,leading to the decrease of peak stress.Under the given thermal deformation conditions,the microstructure is mainly controlled by low angle boundaries,and the main softening mechanism is characterized by dynamic recovery.Amounts of Al3 Zr particles with the size of 10~25nm are generated after adding minor Zr in Al-Zn-Mg-Cu alloy,which can pin dislocations and subgrain boundaries to inhibit recrystallization during deformation,which are responsible for the alloy keeping dynamic recovery microstructure under the given hot deformation conditions.

关 键 词：AL-ZN-MG-CU铝合金 热压缩变形 动态软化 

分 类 号：TG146.21[一般工业技术—材料科学与工程]