合金元素Cd和Nd对ZK60镁合金力学性能及腐蚀性能的影响

【作者】 曾祥亮；

【导师】 刘楚明；

【作者基本信息】 中南大学 ， 材料加工工程， 2009， 硕士

【摘要】 本论文以添加合金元素Cd和Nd的ZK60镁合金为研究对象,通过X-射线衍射分析、光学显微镜观察、扫描电镜观察、透射电镜观察等手段,研究了合金元素Cd和Nd对ZK60镁合金热变形行为、显微组织、力学性能及腐蚀性能的影响,实验结果表明:1、ZK60-1.7Nd-0.7Cd镁合金在同一应变速率下,随变形温度提高,动态再结晶晶粒尺寸增大,体积分数增加;在同一温度下,随应变速率增加,动态再结晶晶粒尺寸减小,体积分数减少。2、合金元素Cd和Nd均能细化ZK60镁合金晶粒,Nd细化效果优于Cd,两者共同作用细化效果最佳。同时加入后,铸态平均晶粒尺寸由100μm细化到35μm,挤压态平均晶粒尺寸由20μm左右细化到7μm左右。因Cd与Mg完全互溶,起固溶强化作用;Nd与Mg、Zn发生共晶反应生成Nd₃Mg₆Zn₁₁相,Nd₃Mg₆Zn₁₁相阻碍位错运动,提高合金强度。故同时加入Cd和Nd后,挤压态合金极限抗拉强度由296MPa提高到334MPa,屈服强度由240MPa提高到300MPa。3、ZK60-1.7Nd-0.7Cd合金经T6处理后强度下降,宜采用T5处理。在本实验条件下,最佳T5处理工艺为:120℃/15h。经最佳时效工艺处理后,极限抗拉强度提高到349MPa,屈服强度达到315MPa。4、同时加入Cd和Nd后降低了合金的腐蚀性能,各个状态下ZK60-1.7Nd-0.7Cd合金的腐蚀性能均比ZK60合金差。ZK60-1.7Nd-0.7Cd合金的腐蚀性能T5态（120℃/15h）优于挤压态,挤压态好于铸态。更多还原

【Abstract】 The influence of Cd and Nd on the microstructure,mechanical properties and corrosion resistance of ZK60 alloy was investigated by optical microscopy（OM）,X-ray diffraction（XRD）,scanning electronic microscopy（SEM） and transmission electron microscopy（TEM）.Some experiment results are obtained as follows.1.The dynamically recrystallized grain size and the recrystallization volume fraction of ZK60-1.7Nd-0.7Cd alloy increase with increasing deformation temperature under the same strain rate and reduce with increasing strain rate under the same deformation temperature.2.The addition of Cd or Nd can refine the microstructures and improve the yield strength of ZK60 alloy.The effect of Cd addition on grain refinement is better than that of Nd addition while the effect is the best for the co-addition of Cd and Nd.Cd completely dissolved in Mg matrix,which results in increasing of the yield strength of ZK60 alloy.Owing to the addition of Nd,a Nd₃Mg₆Zn₁₁ phase appears,which blocks the movement of dislocation lines and improve the strength.Owing to the co-addition of Cd and Nd,the grain size of as-cast ZK60 alloy can be refined to 35μm and as-extruded ZK60 alloy can be refined to 7μm.For as-extruded ZK60 alloy,the yield strength can be improved to 300MPa and the ultimate tensile strength can be improved to 334MPa.3.After T6 treatment,the strength of ZK60-1.7Nd-0.7Cd alloy decreased.The heat treatment of as-extruded ZK60-1.7Nd-0.7Cd alloy should adopt T5 treatment.The optimum process condition of T5 treatment is 120℃/15h.After T5 treatment（120℃/15h）,the yield strength of as-extruded ZK60-1.7Nd-0.7Cd alloy increased to 315MPa and the ultimate tensile strength improved to 349MPa.4.Owing to the co-addition of Cd and Nd,the corrosion resistance decreased.The corrosion resistance of as-T5 treatment ZK60-1.7Nd-0.7Cd alloy is better than as-extruded ZK60-1.7Nd-0.7Cd alloy,and as-extruded ZK60-1.7Nd-0.7Cd alloy is better than as-cast ZK60-1.7Nd-0.7Cd alloy.更多还原