添加稀土金屬對Mg-8Al-xRE鎂鋁合金的潛變行為影響之研究
Date Issued
2005
Date
2005
Author(s)
顧鈞豪
DOI
932216E002014
Abstract
For the purposes of both to protect the
environments and to reduce the garbage on the
earth, the properties of magnesium alloys are
just able to meet the requirements of industrial
application. Although, magnesium alloys have
many advantages, but their high temperature
creep strength and high temperature oxidation
resistance are rather poor. Owing to the poor
high temperature behavior of the Mg alloy, its
high temperature application is restricted, such
as the gearbox of autos at 175 , the c ℃ ylinder
head of engines at 200 . The poor creep ℃
property is just because of the Al12Mg17
eutectic phase, which is unstable at high
temperature, and the quick diffusion of
aluminum atoms in magnesium matrix; both
may accelerate the creep speed of Mg-Al alloys
at high temperature. For improving the creep
properties of magnesium alloy at high
temperature, previous researches may be
summarized as the followings: (1) Adding
some active elements to bond with aluminum
atoms for suppressing the Al12Mg17 phases in
Mg-Al alloys. (2) Promoting the secondary
phases to precipitate at the grain boundaries
for pinning the sliding of grain boundaries. (3)
Producing some fine particles of high
temperature stability in magnesium alloys, so
that to restrict the movement of dislocations.
The effects of improving the creep property at
high temperature by rare-earth elements (misch
metal) addition is limited. By adding RE to
Mg-8Al to form Al11RE3, which can suppress
the unstable Al12Mg17 at high temperature and
3
may precipitate at both the grain boundaries
and the magnesium matrix, can be effective to
obstruct the grain boundaries migration and to
restrict the dislocation sliding; and finally to
promote the creep property at high temperature.
The study of the creep properties of this
alloying becomes significant for high
temperature application. Generally speaking,
the final goal of investigating the high
temperature behavior and the effects of the
phase constituents on the creep resistance of the
Mg-8Al by the additions of misch metal have
been reached.
Subjects
Magnesium alloy
Mg-8Al-xRE alloy
Microstructure
Dispersoid strengthening
Creep behaviors
Publisher
臺北市：國立臺灣大學材料科學與工程學系暨研究所
Type
report
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