时效镁合金高分辨tem.pdf

Advanced Materials Research Vols. 15-17 (2007) pp 445-448
Online available since 2006/Feb/15 at
© (ure [1]. It has been reported that
magnesium alloy containing gadolinium exhibits excellent age hardening [2]. Usually, the studies
have been done for the precipitation sequence in Mg-RE alloys. The precipitation sequence in Mg-Gd
binary alloy is described as;
super saturated solid solution (SSSS) → β” (D019, Mg3Gd) → β’ (bco, Mg15Gd3) → β (fcc, Mg5Gd)
[3]. However there are few reports that observe these precipitates in detail by using high-resolution
transmission electron microscope (HRTEM). So, the TEM observation of the metastable phases in
Mg-Gd-Zr alloy was performed in detail by using the HRTEM.

Experimental procedure
The Mg-%Gd-%Zr alloy was used for the present study. The ingot was homogenized at
773K for 6h, and then hot rolled at 773K to 1mm thickness under an argon atmosphere. The sample
was capsulated into pyrex glass tube with argon gas. It was then solution heat-treated at 773K for 1h
and quenched in water. The aging treatment was performed at 473K and 523K. TEM specimens were
cut from aged plate samples and thinned by the twin-jet electropolishing technique with an electrolyte
of 20 percent nitric acid and 80 percent methanol. HRTEM observation was performed us