Microstructures, Tensile Properties and Creep Characteristics of as-Extruded AZ91 Magnesium Alloy Containing Si, Ca and Rare Earth Elements
Abstract
:1. Introduction
2. Materials and Methods
2.1. Casting
2.2. Hot Extrusion
2.3. Tensile Creep Test
3. Results
3.1. Microstructures
3.2. Tensile Properties
3.3. Tensile Creep Characteristics
4. Discussion
5. Conclusions
- The yield strength (YS), ultimate tensile strength (UTS) and elongation (EL) of the as-extruded AZXSE91000 alloy were 351 MPa, 383 MPa and 7.4% at room temperature, respectively. Those were 184 MPa, 225 MPa and 31.8% at 150 °C.
- The steady creep rates of the as-extruded AZXSE91000 alloy could be comparable with that of the as-cast AZ91 alloy under similar experimental condition, whose values were 2.6 × 10−8 s−1 and 9.3 × 10−8 s−1 at 150 °C/40 MPa and 150 °C/60 MPa respectively.
- The creep stress exponent of the as-extruded AZXSE91000 alloy was 3.0 and 3.3 at a temperature of 125 °C and 150 °C respectively, under a stress of 40–100 MPa. The creep activation energy ranged from 150 to 190 kJ/mol within the stress range of 40–100 MPa.
- Dislocation climbing and grain boundary slip should dominantly contribute to the creep of the as-extruded AZXSE91000 alloy. The asymmetric discontinuous precipitation in crept samples revealed that diffusion played an unneglected role during the creep process.
Author Contributions
Funding
Conflicts of Interest
References
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Nominal Alloy | Composition (wt.%) | ||||||
---|---|---|---|---|---|---|---|
Al | Zn | Ca | Si | La | Ce | Mg | |
Mg-9Al-Zn-0.5RE-0.5Ca-0.5Si | 9.16 | 1.12 | 0.45 | 0.49 | 0.19 | 0.32 | Bal. |
Alloys | Temperature | UTS (MPa) | YS (MPa) | EL |
---|---|---|---|---|
AZXSE91000 | R.T. | 383 | 351 | 7.4% |
150 °C | 225 | 184 | 31.8% | |
200 °C | 153 | 136 | 49% | |
AZXSE91100 [19] | R.T. | 318 | 278 | 9.2% |
150 °C | 230 | 222 | 25.9% | |
200 °C | 148 | 139 | 27.5% |
Alloy | Condition | Creep Strain ε (%; 50 h) | Creep Life (h) | Steady-State Creep Rate (s−1) |
---|---|---|---|---|
As-extruded AZXSE91000 alloy | 125 °C/40 MPa | 0.19 | 50 | 3.6 × 10−09 |
125 °C/60 MPa | 0.31 | 50 | 9.7 × 10−09 | |
125 °C/80 MPa | 0.61 | 50 | 2.1 × 10−08 | |
125 °C/100 MPa | 1.52 | 50 | 6.4 × 10−08 | |
150 °C/40 MPa | 0.49 | 50 | 2.6 × 10−08 | |
150 °C/60 MPa | 1.61 | 50 | 9.3 × 10−08 | |
150 °C/80 MPa | 3.00 | 50 | 1.3 × 10−07 | |
150 °C/100 MPa | 4.58 | 50 | 6.0 × 10−07 | |
As-cast AZ91 [25] | 150 °C/50 MPa | - | - | 5.0 × 10−08 |
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Wu, F.; Qin, C.; Zheng, Y.; Pan, W.; Ma, H.; Li, T.; Ye, C.; Ma, X.; Chu, Z.; Cheng, L.; et al. Microstructures, Tensile Properties and Creep Characteristics of as-Extruded AZ91 Magnesium Alloy Containing Si, Ca and Rare Earth Elements. Metals 2019, 9, 954. https://doi.org/10.3390/met9090954
Wu F, Qin C, Zheng Y, Pan W, Ma H, Li T, Ye C, Ma X, Chu Z, Cheng L, et al. Microstructures, Tensile Properties and Creep Characteristics of as-Extruded AZ91 Magnesium Alloy Containing Si, Ca and Rare Earth Elements. Metals. 2019; 9(9):954. https://doi.org/10.3390/met9090954
Chicago/Turabian StyleWu, Fangfang, Cheng Qin, Yuan Zheng, Weijian Pan, Heng Ma, Tingting Li, Cheng Ye, Xiujuan Ma, Zhibing Chu, Liren Cheng, and et al. 2019. "Microstructures, Tensile Properties and Creep Characteristics of as-Extruded AZ91 Magnesium Alloy Containing Si, Ca and Rare Earth Elements" Metals 9, no. 9: 954. https://doi.org/10.3390/met9090954