Z.M. Zhang
,
C.J. Xu
,
X.F. Guo
,
S.Z. Jia
金属学报(英文版)
Mg 2 Si reinforced Mg-Al based composite with
high amount of silicon was prepared by permanent mould casting, and
then extruded by reciprocating extrusion (RE) after the composite
was processed by homogenization heat treatment. The effect of RE
processing on the morphology and size of Mg 2 Si and the
mechanical properties of the composite were investigated, to develop
new ways to refine the Mg 2 Si phase and improve its shape. The
result showed that RE was very useful in refining the Mg 2Si
phase. The more the RE processing passes, the better the refining
effect would be. Moreover, the uniform distribution of Mg 2 Si
phases would be more in the composite. After the composite was
processed by RE for 12 passes, most Mg 2 Si phases were equiaxed,
with granular diameter below 20 um, and distributed uniformly in
the matrix of the composite. The mechanical properties of the
composite could be increased prominently by RE processing, and were
much higher than that in the as-cast state. As the temperature
rises, the tensile strength is reduced. For the composite RE
processed for 12 passes, the tensile strength, yield strength, and
elongation are 325.9 MPa, 211.4 MPa, and 3.3 % at room temperature,
whereas, 288.2 MPa, 207.7~MPa, and 7.8 %, respectively, at
150 C. In comparison with the properties at room
temperature, the tensile strength and yield strength are high and
only decrease by 11.6 and 1.8 at 150 C. The Mg 2 Si
reinforced Mg-Al based composite possesses good heat resistance at
150 C. The excellent resistance to effect of heat is
attributed to the high melting temperature and good thermal
stability of fine Mg 2 Si phases, which are distributed uniformly
in the composite, and effectively hinder the grain boundary gliding
and dislocation movement.
关键词:
Reciprocating extrusion
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