Effect of V on the microstructure and mechanical properties of Mg–10Er–2Cu alloy with a long period stacking ordered structure

doi:10.1016/j.matlet.2014.02.056

Materials Letters

Volume 122, 1 May 2014, Pages 312-314

https://doi.org/10.1016/j.matlet.2014.02.056 Get rights and content

Highlights

•
The effect of a trace amount of vanadium (V) on the long period stacking order (LPSO) phase was investigated.
•
The addition of V has modified the morphology of 18R-type LPSO phase from coarse block-shaped into finer lamellar-shaped.
•
The associated mechanical properties of ternary Mg–Er–Cu alloy were improved.
•
The modification of LPSO phase stemmed from the resultant thermodynamic drive force to promote heterogeneous nucleation.

Abstract

In this study, the effects of a trace amount of vanadium (V) on the long-period stacking ordered (LPSO) phase and the associated mechanical properties of ternary Mg–Er–Cu alloy were investigated. The addition of V has modified the morphology of 18R-type LPSO phase from coarse block-shaped into finer lamellar-shaped. The as-extruded Mg–Er–Cu (V) alloy presented more promising mechanical performance with the tensile stress of 430 MPa and apparent elongation of 11% at room temperature. Simple interpretation based on thermodynamics was also given.

Introduction

During the past decades, Mg and Mg base alloys have attracted intensive researching activities due to their low densities, high specific strength, well shielding characteristics and easy recycle [1]. One of these activities focuses on enhancing their servicing capability applied as structural materials, especially the strength in order to make them to be comparable with the aluminum alloys. In such a case, the long period stacking ordered (LPSO) phase found in some Mg alloys has received more attention due to its excellent strengthening and toughening effects [2], [3], [4], [5].

So far, a variety of LPSO structure composing of 6H, 10H, 14H, 18R and 24R has been observed in the Mg–RE–TM (RE=rare elements: Y, Gd, Tb, Dy, Ho, Er, Tm; TM=transition elements: Zn, Cu, Ni, Co) systems and Mg–Al–Gd alloys [6], [7], [8]. Recently, several efforts have indicated that the Mg alloys could be strengthened further if the morphology of LPSO phase was modified to finer scale by adding minor alloying elements, such as Zr and Sr [9], [10]. It has provided a novel and effective way to improve the strength of Mg alloys with LPSO phase. In this study, the refractory element vanadium which might have the potential to modify the LPSO phase of Mg alloys was chosen to investigate its function on the resultant microstructure and mechanical properties.

Section snippets

Materials and experimental

Ternary Mg–10Er–2Cu alloys with and without 0.3 wt% V was prepared from Mg–Er, Cu–V master alloys and high-purity Cu element. Here, we select 0.3 wt% V to investigate its effect on the precipitated phase of Mg alloys. More works on the effect of various amounts of V on the precipitated phase of Mg alloys are ongoing. Alloy making was conducted in an induction melting furnace under a partial pressure of Ar as the protective gas during both melting and casting. The alloy melts were occasionally

Results and discussion

Fig. 1(a) shows the optical micrograph of the homogenized Mg–10Er–2Cu alloy. Block-shaped phases were sparsely distributed in the grains or at the grain boundaries. Fig. 1(b) shows the optical micrograph of the homogenized Mg–10Er–2Cu (V) sample. Different from the Mg–Er–Cu samples, the addition of V has made more lamellar-shaped phases precipitated throughout all the grains. The volume fraction of precipitated phases of as-homogenized Mg–10Er–2Cu and Mg–10Er–2Cu(V) alloys was about 10% and

Conclusions

The effect of traced V on the long period stacking ordered (LPSO) phase and mechanical properties of Mg–Er–Cu alloys processed by hot extrusion were investigated. The following conclusions could be derived:

(1)
The addition of trace amount of V has modified the morphology of 18R long period stacking order (LPSO) phase of the as-extruded alloy from coarse block-shaped into finer lamellar-shaped.
(2)
The modification of LPSO phase stemmed from the resultant thermodynamic drive force to promote

Acknowledgements

The authors gratefully acknowledge the financial support from the National Foundation of Natural Science (no. 51171120) and X.H. Du thanks LEM3 UMR7239 CNRS for the visiting scholar identity.

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Effect of V on the microstructure and mechanical properties of Mg–10Er–2Cu alloy with a long period stacking ordered structure

Highlights

Abstract

Introduction

Section snippets

Materials and experimental

Results and discussion

Conclusions

Acknowledgements

Scr Mater

Scr Mater

Mater Lett

Acta Mater

Acta Mater

Intermetallics

Scr Mater

Mater Sci Eng, A

Scr Mater

Mater Des