Carneiro Íris, Fernandes José Valdemar, Simões Sónia
DEMM, Department of Metallurgical and Materials Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal.
LAETA/INEGI, Institute of Science and Innovation in Mechanical and Industrial Engineering, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal.
Nanomaterials (Basel). 2021 May 28;11(6):1426. doi: 10.3390/nano11061426.
The strengthening effect of carbon nanotubes (CNTs) in metal matrix nanocomposites occurs due to several mechanisms that act simultaneously. The possible strengthening mechanisms for metal matrix nanocomposites reinforced with CNTs consist of: (1) load transfer, (2) grain refinement and texture strengthening, (3) second phase strengthening, and (4) strain hardening. The main focus of this work is to identify the strengthening mechanisms that play a role in the case of the Ni-CNT nanocomposite produced by powder metallurgy. For the dispersion and mixing of the metallic powders with CNTs, two different routes were performed by ultrasonication and ball milling. The results indicated that four different strengthening mechanisms are present in the nanocomposites and had a different contribution to the final mechanical properties. The load transfer and the increase in dislocation density seem to strongly affect the properties and microstructure of the nanocomposite. The grain refinement and the presence of second phase particles have a small contribution in the strengthening of this nanocomposite, since the introduction of CNTs in the Ni matrix slightly affects the size and orientation of the grains in the matrix and a few nanometric particles of NiC were identified.
碳纳米管（CNTs）在金属基纳米复合材料中的强化作用是由多种同时起作用的机制引起的。碳纳米管增强金属基纳米复合材料的可能强化机制包括：（1）载荷传递，（2）晶粒细化和织构强化，（3）第二相强化，以及（4）应变硬化。这项工作的主要重点是确定在通过粉末冶金制备的镍-碳纳米管纳米复合材料中起作用的强化机制。为了使金属粉末与碳纳米管分散和混合，通过超声处理和球磨进行了两种不同的途径。结果表明，纳米复合材料中存在四种不同的强化机制，并且对最终力学性能有不同的贡献。载荷传递和位错密度的增加似乎强烈影响纳米复合材料的性能和微观结构。晶粒细化和第二相颗粒的存在对这种纳米复合材料的强化贡献较小，因为在镍基体中引入碳纳米管对基体中晶粒的尺寸和取向影响较小，并且鉴定出了一些纳米级的NiC颗粒。
