S. C. Hogg
Microstructure and property development in spray formed and extruded Al-Mg-Li-Zr alloys for aerospace and autosport applications
Hogg, S. C.; Mi, J.; Nilsen, K. E.; Liotti, E.; Grant, P. S.
Professor Jiawei Mi J.Mi@hull.ac.uk
Professor of Materials
K. E. Nilsen
P. S. Grant
Low density Al-4Mg-1.3Li-0.4Zr and Al-6Mg-1.6Li-0.4Zr alloys were spray formed and the billets extruded under a range of conditions. The alloy compositions were selected to provide an attractive balance of tensile strength and elongation, without relying on complex post-processing and heat treatments - and are therefore suitable for complex cross section extrusions and free from quench distortion. The as-spray formed microstructures showed fine homogeneous, equiaxed grains with an average size of 10-15 lm. Firstly, a laboratory scale extrusion was carried out to extrude 30 mm diameter billets into 7.5 mm diameter cross-section and to investigate the effects of temperature and ram speeds on microstructural development. The microstructure after extrusion at 4008C was partially dynamically recrystallised with a l0.5 area fraction of l1 lm grains and the remainder were unrecrystallised elongated grains. Electron backscatter diffraction showed a mixed a111A + a100A double fibre texture. After peak age hardening at 1508C for 96 h, the Al-6Mg-1.6Li-0.4Zr alloy showed a 0.2% proof strength of 495 MPa, a tensile strength of 553 MPa and elongation to failure of 8.5%; Al-4Mg-1.3Li-0.4Zr showed a 0.2% proof strength of 392 MPa, a tensile strength of 476 MPa and an elongation of 10%. Subsequently, large-scale complex cross-section were extruded at l4008C. Due to the complexity of the cross-sections and the non-axisymetric deformation, the fibre texture was distorted to FCC rolled Copper and Brass orientations. After a dual-step age hardening treatment of 1308C for 8h followed by 1608C for 8h, the proof strength, ultimate strength and elongations were 340 MPa, 470 MPa and 16% respectively. The combination of relatively simple process steps, high strength and ductility/formability, and low distortion in complex sections demonstrated the strong potential for these low density alloys in aerospace and autosport applications.
|Journal Article Type||Article|
|Publication Date||Jul 1, 2010|
|Journal||Materialwissenschaft und Werkstofftechnik|
|Peer Reviewed||Peer Reviewed|
|APA6 Citation||Hogg, S. C., Mi, J., Nilsen, K. E., Liotti, E., & Grant, P. S. (2010). Microstructure and property development in spray formed and extruded Al-Mg-Li-Zr alloys for aerospace and autosport applications. Materials Science and Engineering Technology / Materialwissenschaft und Werkstofftechnik, 41(7), 562-567. doi:10.1002/mawe.201000643|
|Keywords||Mechanical Engineering; General Materials Science; Mechanics of Materials; Condensed Matter Physics|