Structure and property evolutions of ECAPed 7075 Al alloy during annealing.

Conference · Thu Jan 01 04:00:00 EST 2004

OSTI ID:977445

Zhao, Y ^[1]; Liao, Xiaozhou; Zhu, Y T ^[2]; Valiev, R Z ^[3]

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1. Yonghao
2. Yuntian Theodore
3. Ruslan Zufarovich

Structure and microhardness evolutions of equal-channel angular pressing (ECAP) processed and coarse-grained (CG) 7075 A1 alloys during differential scanning calorimeter (DSC) were investigated by x-ray diffraction (XRD), transmission electron microscopy (TEM) and microhardness measurements. After one-month aging at room temperature, the microhardness of the ECAP processed sample is about 50% larger than that of the CG sample. During DSC annealing, the microhardness of the ECAP processed sample decreased gradually, while a hardening peak appeared for the CG sample. XRD and TEM show that the hardening peak of the CG sample was mainly caused by the precipitation hardening of the Guinier-Preston (GP) zone. For the ECAP processed sample, upon annealing the microstrain (dislocation density) decreased and the crystallites grew, which decreased the hardness and overcompensated the GP zone precipitation hardening. DSC analysis indicates ECAP process only promoted the phase precipitation, but did not change the sequence of phase precipitation.

• Research Organization: Los Alamos National Laboratory
• Sponsoring Organization: DOE
• OSTI ID: 977445
• Report Number(s): LA-UR-04-0649; LA-UR-04-649
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
AGING
ALLOYS
ANNEALING
CALORIMETERS
GLOBAL POSITIONING SYSTEM
HARDENING
HARDNESS
MICROHARDNESS
PRECIPITATION
PRECIPITATION HARDENING
PRESSING
TRANSMISSION ELECTRON MICROSCOPY
X-RAY DIFFRACTION