Effect of Ti addition on the thermal stability of nanocrystalline AZ61 Mg alloy
Effect of Ti addition on the thermal stability of nanocrystalline AZ61 Mg alloy
复制标题
Ti添加量对纳米晶AZ61镁合金热稳定性的影响
DOI：
10.1016/j.jallcom.2022.164266
复制
发表时间：
2022-02-23
影响因子：
6.2
通讯作者：
Yu, Huan
中科院分区：
文献类型：
--
作者：
Su, Qian;Wang, Rongrong;Yu, Huan
纳米结构的合金具有特别理想的性能，但由于原子处于非平衡晶格位置的晶界含量高，因此热稳定性低。本文对纳米晶Ti/AZ 61镁基复合材料（AZ 61 Mg-Ti）在573 ~ 723 K之间进行了等温退火。随后，以纳米晶AZ 61镁合金为对比对象，对其热稳定性进行了分析。在723 K退火600 min后，AZ 61 Mg-Ti合金的平均晶粒尺寸约为95 nm，远小于退火态AZ 61合金的晶粒尺寸（~ 450 nm）。Ti颗粒尺寸约为-410 nm，纳米Ti 3Al颗粒尺寸约为-8 nm，均匀分布在镁基体中。用广义抛物线晶粒生长模型D-8 - D-0（8）= kt较好地解释了纳米晶AZ 61 Mg-Ti的晶粒生长动力学。晶粒长大的激活能（E-g）为134 kJ/mol，比纯Mg高42 kJ/mol。对于E-g，计算出拖曳效应和钉扎效应对提高热稳定性的贡献率分别为62%和38%。研究了退火试样的硬度变化规律，发现随着退火温度的升高，由于非热敏性Ti颗粒的影响和Mg晶粒的限制，AZ 61 Mg-Ti合金的硬度下降趋势比AZ 61合金平缓。经723 K × 600 min退火处理后，AZ 61合金的硬度为1.27 GPa，高于退火态AZ 61合金的1.13 GPa。(c)2022爱思唯尔有限公司版权所有。
Nanostructured alloys possess exceptional desirable properties but suffer from low thermal stability, as a consequence of a high content of grain boundaries where the atoms are in non-equilibrium lattice positions. Here nanocrystalline Ti/AZ61 magnesium matrix composite (AZ61Mg-Ti) was annealed isothermally be-tween 573 K and 723 K. Subsequently, the thermal stability was analyzed, taking nanocrystalline AZ61 alloy as the comparative object. After annealing at 723 K for 600 min, the average grain size of AZ61Mg-Ti was approximately 95 nm, much less than that for the annealed AZ61 alloy (-450 nm). And Ti particles with size of -410 nm and nano scale Ti3Al particles with size of -8 nm were uniformly distributed in magnesium matrix. The kinetics of magnesium grain growth for nanocrystalline AZ61Mg-Ti, was well interpreted by generalized parabolic grain growth model, D-8 - D-0(8) = kt . The activation energy (E-g) for grain growth was calculated to be 134 kJ/mol, being 42 kJ/mol higher than that for pure Mg. For E-g, the contribution rates of drag effect and pinning effect to improve thermal stability were calculated to be 62% and 38%, respectively. Hardness evolution of annealed samples was studied and with raising annealing temperature the down -trend for AZ61Mg-Ti was more gradual than for AZ61 alloy due to the effect of the non-thermal sensitive Ti particles and the restricted Mg grain growth. After annealing treatment at 723 K for 600 min, the hardness was 1.27 GPa, higher than that for the annealed AZ61 (1.13 GPa). (c) 2022 Elsevier B.V. All rights reserved.