Abstract
This study investigates the effect of the α/C14 interface on the creep strength of α-Mg/C14–Mg2Ca eutectic alloy at 473 K under a stress of 40 MPa. The α/C14 interface is composed of terraces and steps, with terraces parallel to the (1101)α pyramidal plane of the α-Mg lamellae and to the (1120)C14 columnar plane of the C14–Mg2Ca lamellae. The creep curves of the alloy exhibit three stages: a normal transient creep stage, a minimum creep rate stage, and an accelerating stage. The minimum creep rate is proportional to the lamellar spacing, indicating that the α/C14 lamellar interface plays a creep-strengthening role. In the high-resolution transmission electron microscopy image captured of the specimen after the creep test, <a> dislocations can be mainly seen within the soft α-Mg lamellae, and they are randomly distributed at the α/C14 interface. In contrast, dislocations are rarely introduced in the hard C14–Mg2Ca lamellae. It is deduced that the α/C14 interface presents a barrier to dislocation gliding within the α-Mg lamellae and does not help rearrange the dislocations.
Highlights
Magnesium alloys are gaining interest as lightweight structural materials in the aerospace and automotive industries to achieve high fuel efficiency and reduce the emission of carbon dioxide [1]
The intermetallic phases with high thermal stability, which are available as covering phases [7,8] and/or precipitation phases [9,10], are essential for enhancing the high-temperature strength of heat-resistant magnesium alloys [11,12]
The2 Ca objective lamellae through a detailed observation; second, to quantitatively clarify the study were to elucidate the following three points by using a Mg–Ca alloy with interrelation between creep strength and λ, where λ was controlled by aging at 673 K; finethird, lamellar microstructure: first, to clarifyonthe orientation relationship and to clarify the role of the lamellar interface dislocation gliding, through the betwee and C14–Mg
Summary
Magnesium alloys are gaining interest as lightweight structural materials in the aerospace and automotive industries to achieve high fuel efficiency and reduce the emission of carbon dioxide [1]. The intermetallic phases with high thermal stability, which are available as covering phases [7,8] and/or precipitation phases [9,10], are essential for enhancing the high-temperature strength of heat-resistant magnesium alloys [11,12]. In the effec elucidate the following three points by using a Mg–Ca alloy with a α/C14 contrast, fine lamellar microstructure: first, to clarify the orientation relationship between α-Mg alloys. HRTEM observation; second, to quantitatively clarify the study were to elucidate the following three points by using a Mg–Ca alloy with interrelation between creep strength and λ, where λ was controlled by aging at 673 K; finethird, lamellar microstructure: first, to clarifyonthe orientation relationship and to clarify the role of the lamellar interface dislocation gliding, through the betwee and C14–Mg. HRTEM observation; second, to q observation of dislocation substructure of the creep specimens. A binary alloy of composition Mg–13.8 mass% Ca was cast at Mitsui Mining & Smelting ing, through the observation of dislocation substructure of the creep specimens
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