电解铝液制备的7005铝合金铸态拉伸断口分析

通过室温拉伸试验研究了电解铝液制备的7005合金铸态力学性能,并采用光学显微镜观察、扫描电镜观察及能谱分析等手段对拉伸断口及其纵截面的组织形貌进行分析.结果表明,电解铝液中的Fe、Si、H2、Al2O3夹杂对7005合金铸态力学性能有显著影响.铝电解过程中生成的H2和Al2O3夹杂,是铸锭中形成疏松、夹杂的原因.电解铝液中的Fe、Si杂质元素与合金中的Mn、Mg等元素作用形成硬脆、粗大的AlFeMnSi、Mg2Si等第二相,分布于晶内以及晶界处.试样的断裂主要是由夹杂物、疏松孔洞及AlFeMnSi脆性相等裂纹源的综合作用而引起的,拉伸断裂的模式为穿晶方式的韧窝-准解理混合型断裂.

Tensile Fracture Morphology of As-cast 7005 Aluminum Alloy Produced by Electrolytic Liquid Al

Tensile strength of as-cast 7005 aluminum alloy produced by electrolytic liquid Al was measured by means of room temperature tensile testing. Fracture morphology and longitudinal microstructure were observed by OM (optical microscope) and SEM (scanning electron microscope) as well as EPA (energy spectrum analysis). The results indicate that tensile strength of as-cast 7005 alloy is distinctly dependent on the Fe, Si, H and Al_2O_3 inclusions in electrolytic liquid Al. Shrinkage porosity and inclusions in aluminum ingot are controlled by creation of H_2 and Al_2O_3 inclusions in electrolytic liquid Al. The hard brittle coarse second phase, such as AlFeMnSi, Mg_2Si phase, are formed by the reaction of impurity elements Fe, Si in electrolytic liquid Al with alloy elements Mn, Mg, which is distributed in grains and on the grain boundaries. The fracture of the samples is attributed to the co-action of inclusions, shrinkage porosity and brittle AlFeMnSi phases. Tensile fracture mechanism of as-cast 7005 aluminum alloy is characterized by dimple-quasi-cleavage features of trangranular model.