Effect of annealing treatment on the microstructure and mechanical properties of bulk nanostructured Ti/AZ61 composites prepared by hot pressing
Effect of annealing treatment on the microstructure and mechanical properties of bulk nanostructured Ti/AZ61 composites prepared by hot pressing
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DOI：
10.1016/j.jmrt.2023.06.015
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发表时间：
2023-06-17
影响因子：
6.4
通讯作者：
Hu，Lianxi
中科院分区：
文献类型：
--
作者：
Su，Qian;Han，Yejin;Hu，Lianxi
镁合金作为最轻的结构合金，提供了通过提高能源效率来解决环境问题的可能性。纳米晶基体的开发和维护是一项巨大的挑战，也是实现超高强度的关键。对热压法制备的纳米晶Ti/AZ61复合材料进行退火处理，通过SEM、XRD和TEM对其微观组织演变进行表征，包括镁基体、Ti分散体和纳米级析出相的变化。对退火后复合材料的密度和力学性能进行了测试和分析。在623 K下退火80 h后，纳米晶Ti/AZ61复合材料的平均晶粒尺寸为102 nm， 97%的Ti分散体为亚微米级，Ti3Al析出相保持纳米级。Ti弥散体和Ti3Al析出相均匀分布在镁基体中。与热压复合材料相比，退火复合材料由先验颗粒边界（PPB）产生的裂纹受到抑制。退火后Ti/AZ61复合材料的密度和PPB结合强度的提高对其强度和塑性有积极的影响。退火处理40 h后，密度从~ 2.041 g/cm3增加到2.066 g/cm3。硬度、屈服强度和FFS分别为146 HV、493 MPa和5.6%，相应的增幅分别为7%、12%和65%。
Magnesium alloys, as the lightest structural alloys, provide the possibility of solving environmental problems by improving energy efficiency. Developing and maintaining nanocrystalline matrix is a huge challenge, and the key to achieving ultra-high strength. The nanocrystalline Ti/AZ61 composite prepared by hot pressing was annealed, and its microstructural evolution was characterized via SEM, XRD, and TEM, including the changes in magnesium matrix, Ti dispersions, and nano-scale precipitates. The density and mechanical properties of annealed composites were tested and analyzed. After annealing treatment at 623 K for 80 h, the average grain size of nanocrystalline Ti/AZ61 composites was 102 nm. 97% of Ti dispersions were submicron sized, and Ti3Al precipitates remained nanometer-sized. Ti dispersions and Ti3Al precipitates were uniformly distributed in the magnesium matrix. Compared with hot pressed composites, the crack that originated from the prior particle boundary (PPB) was restrained for annealed composites. The improved density and PPB bonding strength of annealed Ti/AZ61 composites had a positive impact on strength and plasticity. After annealing treatment for 40 h, the density increased from ∼2.041 g/cm3to 2.066 g/cm3. The hardness, yield strength, and FFS were 146 HV, 493 MPa, and 5.6%, respectively, with corresponding increasing rates of 7%, 12%, and 65%, respectively.