Kim Yong-Ho, Yoo Hyo-Sang, Son Hyeon-Taek
Automotive Components and Materials R&D Group, Korea Institute of Industrial Technology, 6, Cheomdangwagi-ro 208 beon-gil, Buk-gu, Gwangju, 61012, Korea.
J Nanosci Nanotechnol. 2018 Sep 1;18(9):6304-6308. doi: 10.1166/jnn.2018.15637.
Magnesium and its alloys are potential candidates for many automotive and aerospace applications due to their low density and high specific strength. However, the use of magnesium as wrought products is limited because of its poor workability at ambient temperatures. Mg-Li alloys containing 5-11 wt.% Li exhibit a two-phase structure consisting of a α (hcp) Mg-rich phase and a β (bcc) Li-rich phase. Mg-Li alloys with Li content greater than 11 wt.% exhibit a single-phase structure consisting of only the β phase. In the present study, we studied the effects of Y addition on the microstructure and mechanical properties of Mg-11Li-6Zn-0.6Zr-0.4Ag-0.2Ca based alloys. The melt was maintained at 720 °C for 20 min and poured into a mold. Then, the as-cast Mg alloys were homogenized at 350 °C for 4 h and were hot-extruded onto a 4-mm-thick plate with a reduction ratio of 14:1. The as-cast Mg-11Li-6Zn-0.6Zr-0.4Ag-0.2Ca-xY (x 0, 1, 3, and 5 wt.%) alloys were composed of α-Mg, β-Li, γ-Mg2Zn3Li, I-Mg3YZn6, W-Mg3Y2Zn3, and X-Mg12YZn phases. By increasing the Y content from 0 to 5 wt.%, the composition of the W-Mg3Y2Zn3 phase increased. With increasing Y content, from 0 to 1, 3, and 5 wt.%, the average grain size and ultimate tensile of the as-extruded Mg alloys decreased slightly, from 8.4, to 3.62, 3.56, and 3.44 μm and from 228.92 to 215.57, 187.47, and 161.04 MPa, respectively, at room temperature.
镁及其合金因其低密度和高比强度而成为许多汽车和航空航天应用的潜在候选材料。然而，由于镁在室温下加工性能较差，其作为锻造产品的应用受到限制。含5-11 wt.%锂的Mg-Li合金呈现出由α（hcp）富镁相和β（bcc）富锂相组成的两相结构。锂含量大于11 wt.%的Mg-Li合金呈现出仅由β相组成的单相结构。在本研究中，我们研究了添加Y对Mg-11Li-6Zn-0.6Zr-0.4Ag-0.2Ca基合金微观结构和力学性能的影响。熔体在720°C下保持20分钟，然后倒入模具中。然后，铸态镁合金在350°C下均匀化4小时，并热挤压成厚度为4毫米的板材，挤压比为14:1。铸态Mg-11Li-6Zn-0.6Zr-0.4Ag-0.2Ca-xY（x = 0、1、3和5 wt.%）合金由α-Mg、β-Li、γ-Mg2Zn3Li、I-Mg3YZn6、W-Mg3Y2Zn3和X-Mg12YZn相组成。通过将Y含量从0 wt.%增加到5 wt.%，W-Mg3Y2Zn3相的成分增加。随着Y含量从0 wt.%增加到1 wt.%、3 wt.%和5 wt.%，挤压态镁合金的平均晶粒尺寸和室温下的极限抗拉强度略有下降，分别从8.4微米降至3.62微米、3.56微米和3.44微米，从228.92兆帕降至215.57兆帕、187.47兆帕和161.04兆帕。
