变形锌铜钛合金蠕变行为及其组织与性能研究

【作者】 张喜民；

【导师】 肖来荣；

【作者基本信息】 中南大学 ， 材料学， 2010， 硕士

【摘要】 采用熔铸、挤压等方法制备了一系列Zn-Cu-Ti、Zn-Cu-Ti-Cr、Zn-Cu-Ti-Mn、Zn-Cu-Ti-Mg、Zn-Cu-Ti-Al等锌铜钛合金,借助光学显微镜(OM)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、差热分析仪(DSC)、X射线衍射仪(XRD)、能谱分析仪(EDS)以及蠕变试验机等手段和设备,研究了不同合金成分及含量的锌铜钛合金的微观组织及相组成,对比研究了合金化对合金力学性能的影响,建立了合金再结晶晶粒长大模型及高温蠕变本构方程,初步探讨了合金的高温蠕变机理及Cr对合金再结晶行为和常温蠕变行为的影响。得出以下结论：(1) Zn-0.5～3.0Cu-0.1～0.3Ti合金的熔点在419.7℃～422.6℃之间；变形锌铜钛合金的相组成主要包括η相、ε相和TiZn15相；250℃热挤压过程合金发生了动态再结晶,第二相能够抑制再结晶晶粒长大。(2)随着Cu、Ti含量的升高合金的强度升高,伸长率则先升后降；分别添加微量Cr、Mn、Mg、Al提高了Zn-1.0Cu-0.2Ti合金的强度；添加微量Mg的合金强度达280MPa。(3) Zn-1.0Cu-0.2Ti合金与Zn-1.0Cu-0.2Ti-0.1Cr合金的再结晶温度分别为230℃和260℃；Zn-1.0Cu-0.2Ti合金再结晶晶粒长大的热激活能为49.96 kJmol-1。Zn-1.0Cu-0.2Ti合金的再结晶晶粒长大模型：D2= 21.47+533851.14te(6009.14/T)(4)Zn-1.0Cu-0.2Ti合金的蠕变激活能为83.7 kJmol-1,高温蠕变本构方程可以表示为：ε= 5.32×10-3σ5.10 exp(-83700/RT); Zn-Cu-Ti合金高温蠕变过程中,高温蠕变主要机制为自扩散控制机制。常温蠕变中主要机制为晶粒内部位错滑移和攀移机制；Zn-1.0Cu-0.2Ti-0.1Cr合金的常温抗蠕变性能优于Zn-1.0Cu-0.2Ti合金。更多还原

【Abstract】 A serial of Zn-Cu-Ti、Zn-Cu-Ti-Cr、Zn-Cu-Ti-Mn、Zn-Cu-Ti-Mg、Zn-Cu-Ti-Al alloys were parepared by melting, casting and extruding. This eassay studied the microstructure of the alloys of different compositions with the help of XRD、DSC、SEM、TEM、EDS and so on, revealed the alloying effects on alloys’ mechanical properties, and also estabilished the equation of recrystallization and creep at high temperature, discussed the alloys’ recrystallization mechanism and creep mechanism. The following results were obtained:(1) Zn-0.5～3.0Cu-0.1～0.3Ti alloy melting pointis is between 419.7℃and 422.6℃; Wrought Zn-Cu-Ti alloy is constituted of phase、εphase and TiZn15 phase. During hot extrusion process at 250℃, dynamic recrystallization occurres and the second phase inhibits the recrystallization grain growth.(2) Strength and elongation of the alloys increases with the increase of Cu and Ti elements, but elongation decreases once Ti% is above 0.2%. Trace Cr、Mn、Mg、Al increases the strength of Zn-1.0Cu-0.2Ti alloy; The tensile strength of Zn-1.0Cu-0.2Ti-0.05Mg is up to 280MPa.(3) The recrystallization temperatures of Zn-1.0Cu-0.2Ti alloy and Zn-1.0Cu-0.2Ti-0.1Cr alloy are 230℃and 260℃respectively. The ecrystallization grain growth activation energy is 49.96 KJmol-1. Grain growth equation of the Zn-1.0Cu-0.2Ti alloy is established: D2= 21.47+533851.14te (6009.14/T)(4) The creep activation energy of Zn-1.0Cu-0.1Ti alloy at high temperature is 83.7 KJmol-1. Zn-1.0Cu-0.1Ti alloy constitutive equation can be expressed as:ε= 5.32×10-3σ5.10exp(-83720/RT). The main mechanism of high temperature creep is controlled mainly by diffusion mechanisms. the main mechanism is the sliling and climbing mechanism of dislocation during the creep period at room temperature. Zn-1.0Cu-0.2Ti-0.1Cr alloy shows a better creep property than the Zn-1.0Cu-0.2Ti alloy at 25℃.更多还原