论文部分内容阅读
为改善力学性能,采用新型Al-5Ti-1B-1RE中间合金细化剂和Al-10Sr中间合金变质剂对铸态多元铝硅A356铝合金及在铸态A356铝合金中按一定比例添加Cu、Mn、Ti等元素组成的新型铝合金进行复合细化变质处理.采用光学显微镜(OM)、扫描电镜(SEM)及能谱(EDS)、透射电镜(TEM)和电子式万能试验机(CSS-44100)等技术对多元铝硅合金中的第二相粒子的形态分布特征及强化机制进行分析.结果 表明:经复合细化变质处理的A356铝合金中的第二相粒子共晶硅相由粗大的片层状转变为典型的纤维状,在软韧相α-Al基体晶界处较均匀地析出,α-Al相晶粒尺寸显著变小,其强化机制主要是第二相粒子共晶硅Hall-Petch晶界细晶强化;在新型铝合金中除第二相粒子共晶硅外,还存在其它弥散分布在晶界或晶内的第二相强化粒子,多种强化机制共同起作用.当强化粒子分布在晶界上时,主要是Hall-Petch强化机制;当分布在晶内时,主要是Orowan强化机制,成为阻碍位错运动的有效障碍,起到强化作用.“,”In order to improve the mechanical properties,a new Al-5Ti-1B-1RE master alloy refiner and Al-10Sr master alloy modifier were used to composite refine and modify the as-cast A356 aluminum alloy and a novel aluminum alloy composed of as-cast A356 aluminum alloy by adding Cu,Mn,Ti and other elements in a certain proportion.The morphology distribution of the second-phase particles and strengthening mechanism of the multi-component aluminum-silicon alloy were analyzed by OM,SEM,EDS,TEM and the electronic universal testing machine (CSS-44100).The results show that the second-phase eutectic silicon phase in the A356 aluminum alloy transforms from coarse lamellar to typical fibrous phase after the composite refinement and modification,and precipitates uniformly at the grain boundary of the soft-tough phase α-Al matrix.The grain size of the α-Al phase decreases significantly.It is mainly Hall-Petch grain boundary fine grain strengthening mechanism.In addition to the second-phase particle eutectic silicon in the novel aluminum alloy,there are other second-phase particles which are dispersed in the grain boundaries or intragranular.Various strengthening mechanisms work together.When the second-phase particles distribute on grain boundaries,it is mainly the Hall-Petch strengthening mechanism.When the second-phase particles distribute in intragranular,it is mainly Orowan strengthening mechanism,which becomes an effective obstacle to dislocation movement and plays a strengthening role.