Microstructure evolution and densification of sintered porous 2024 aluminum alloy compressed in a semi-solid state

Abstract

The semi-solid powder forming (SSPF) as a promising technology has a complicated process, but the formation mechanism of that remains unclear. The study of semi-solid compression of porous materials is an effective method to investigate the SSPF. Based on analyzing the influence of deformation strain, temperature, strain rate and initial relative density on microstructure evolution and relative density development of sintered porous 2024 aluminum alloy during semi-solid compression, the deformation mechanism and densification mechanism of semi-solid porous materials were proposed. The results show that main deformation mechanisms of porous materials during semi-solid compression are breakup of the solid skeleton or powders, and flowing of liquid with powders or fragments. Breakup mechanism is dominant at center area, whereas flowing mechanism dominates at the margin. With increasing strain and temperature and decreasing strain rate, breakup mechanism becomes primary. The densification mechanisms of porous materials during semi-solid compression are rearrangement of powders or fragments and filling of liquid, resulting from collapse of the solid skeleton or powders and flowing of liquid. The emergence of pores and densification occur simultaneously during semi-solid compression of porous materials.

Keywords

• semi-solid compression
• sintered porous material
• 2024 aluminum alloy
• densification mechanism
• deformation mechanism