Isochronal study of Al-Mg, Al-Mn, and Al-Mn-Mg alloys using electrical resistivity and thermoelectric power

Materials Research

Ney José Luiggi Agreda¹ 

关键词: Al-Mn;    Al-Mg;    Al-Mn-Mg Alloys;    phase precipitation kinetics;    electrical resistivity;    thermoelectric power;    aluminum alloys of the 3000 series;   

DOI  :  10.1590/S1516-14392005000100007

来源: SciELO

【 摘 要 】

We have studied the phase transformation kinetics occurring in aluminum alloys containing Mn, Mg, and Mn-Mn-Mg by means of electrical resistivity (rho) and thermoelectric power (deltaS). The alloy samples were annealed isochronally at temperatures ranging from ambient temperature to 615 °C. Both rho and deltaS allowed the separation of several stages of transformation associated to either the precipitation or dissolution of phases that occur during the annealing process. The alloys containing Mn show a strong deltaS growth or a marked r drop between 450 °C and 550 °C, linked to the precipitation of the Mn-rich Al6(Mn,FE) equilibrium phase. While the Mg in aluminum generates a series of maxima and minima of both rho and deltaS associated to the pre-established precipitation sequence: GP Zones ® b' phase ® b phase, a combination of effects ensues in the Mn- and Mg-containing alloys, the Mg effect being enhanced at temperatures below 350 °C and that of the Mn striking the same behavior above such temperature. Our study ascertains that the Mg speeds up the precipitation and lowers the activation energy of the Al6(Mn,Fe) phase, the latter having been evaluated by the multiple temperature method.

【 授权许可】

CC BY   
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