1 School of Materials and Metallurgy, Inner Mongolia University of Science &Technology, Baotou 014010, China. 2 Analysis and Test Center, Inner Mongolia University of Science & Technology, Baotou 014010, China
Cite this article:
Zhenliang LI,Fei LIU,Aiping YUAN,Baoyu DUAN,Xiaowei LI,Yiming LI. EFFECTS OF ROLLING DEFORMATION ON TEXTURE AND LPSO PHASE OF SPRAY-DEPOSITED MAGNESIUM ALLOYS CONTAINING Nd. Acta Metall Sin, 2016, 52(8): 938-944.
Mg alloys have been applied widely as structural materials over the past decades, with low density, high specific strength, stiffness, specific elastic modulus, and high recycling rate. However, their features of poor ductility and formability at room temperature have limited their application due to hexagonal close-packed crystal structure with less independent slip systems. Grain refinement and texture randomization are two means to activate other slip systems. In this work, the billets of Mg-9Al-3Zn-1Mn-6Ca-2Nd alloy produced by spraying deposition method (the Osprey process) were studied in order to analyze the effect of rolling deformation at 350 ℃ and pass reduction ε =20%, 25% and 30% on texture and microstructure evolution of an extruded size-asymmetry Mg alloy by SEM, TEM and XRD. The results show that under the condition of reduction of ε =20% at 350 ℃, a long-period stacking ordered phase with 24R structure was formed in (Ca, Nd)Al2 phase (C15 Laves phase ). All of basal texture (0002), prismatic texture {100}<0001>, and pyramidal texture {102} were activated, with pole density level weakened while pass reduction increased (ε =20%, 25% and 30%), namely, texture randomization achieved in Mg alloy, with main causes of nanometer-sized dispersed C15 phase impeding dislocation movement and sub-cells inducing the process of recrystallization.
Fig.1 (0002), (100) and (102) pole figures of spray-deposited Mg alloy sheet after different reductions (ε—pass reduction) (a) ε =20% (b) ε =25% (c) ε =30%
Fig.2 SEM images of spray-deposited Mg alloy sheet after different reductions at 350 ℃ (a) ε =20% (b) ε =25% (c) ε =30%
Fig.3 TEM images and structural analysis of secondary phase in Mg alloy after reductions of ε =20% at 350 ℃ (a, b) TEM images of secondary phase in Mg alloy(c) SAED pattern of lamellar secondary phase in Fig.3b(d) HRTEM image of lamellar secondary phase in Fig.3b
Area
Mass fraction / %
Atomic fraction / %
Mg
Al
Ca
Nd
Zn
Mg
Al
Ca
Nd
Zn
A
38.4
22.9
28.5
7.4
2.8
49.1
26.1
21.9
1.6
1.3
B
57.1
21.0
13.8
5.4
2.7
67.2
21.3
9.4
1.0
1.1
C
40.3
23.6
20.0
8.9
7.2
51.8
27.3
15.6
1.9
3.4
Table 1 EDS analytic results of areas A, B and C in Fig.3
