Microstructure and mechanical properties of AA7039+20%SiC W composite

Area of Science:

• Materials Science
• Metallurgy
• Composite Materials

Background:

• Aluminum alloys like AA7039 are crucial in aerospace and automotive industries.
• Reinforcement with silicon carbide (SiC) whiskers enhances mechanical properties of aluminum matrices.
• Understanding deformation behavior is key for optimizing processing and performance.

Purpose of the Study:

• To investigate the hot deformation behavior of AA7039 reinforced with 20% SiC whiskers.
• To analyze the microstructural evolution of the composite under varying temperatures.
• To determine the origin of observed microstructural features in SiC whiskers.

Main Methods:

• Hot deformation tests were conducted on the composite material.
• Flow stress was measured across a range of temperatures (293 K to 823 K).
• Transmission Electron Microscopy (TEM) was used for microstructural analysis of deformed samples.

Main Results:

• Maximum flow stress decreased significantly from 640 MPa at 293 K to approximately 8 MPa at 823 K.
• TEM revealed a recovered substructure in the AA7039 matrix.
• Striated structures, identified as nano-sized twins and stacking faults, were observed within SiC whiskers.

Conclusions:

• The hot deformation temperature strongly influences the flow stress of AA7039/SiC composites.
• The observed microstructural features in SiC whiskers likely originate from crystal growth, not the deformation process.
• This research provides insights into the deformation mechanisms and microstructural stability of SiC-reinforced aluminum composites.