Abstract
Tensile fractured surface of annealed 5083 aluminum alloy sheet was examined by electron microfractography and electron beam scanning image analysis in order to study the relationship between the inclusions and tensile fracture characteristics at room temperature.
According to the electron beam scanning image analysis, Mn and Fe were usually segregated in the exact same location of the tensile fractured surface. Occasionally, segregation of Cr and Si was observed in the above location. Remarkable segregation of Si and Mg was also confirmed in the different location of the tensile fractured surface.
The former segregation was considered to be due to an intermetallic compound, such as Al6Fe Mn, consisting mainly of Fe, Mn and Al, while the latter segregation was considered to be due to another kind of intermetallic compound, such as Mg2Si, consisting primarily of Mg and Si.
The Al-Fe-Mn intermetallic compound was usually large in size ranging from about 5 to 10 microns and existed preferentially in large dimples, especially in the inner wall or bottom portion of the dimples. The Mg-Si intermetallic compound was usually smaller in size ranging from about 1 to 2 microns estimated by the electron scanning image and existed preferentially in the neighborhood of the opening portion of the dimples. Thus, such an intermetallic compound consisting primarily of Fe, Mn and Al was considered to be directly and most closely related to formation of large size dimples, indicating that voids or microcracks were initiated primarily at these inclusion particles either by decohesion from the matrix or by cleavage of the particles.
Besides Al-Fe-Mn and Mg-Si intermetallic compounds, existence of an Al-Mg intermetallic compound was also observed in the tensile fractured surface of the annealed 5083 aluminum alloy sheet.
