Microstructural evolution and mechanical properties of thermomechanically processed AZ31 magnesium alloy reinforced by micro-graphite and nano-graphene particles

• Published in: Journal of alloys and compounds 2020-01, Vol.815, p.152231, Article 152231
• Main Authors: Vahedi, F., Zarei-Hanzaki, A., Salandari-Rabori, A., Abedi, H.R., Razaghian, A., Minarik, P.
• Format: Article
• Language: English
• Subjects: Brittle fracture; Clustering; Deformation; Diamond pyramid hardness; Ductile fracture; Ductile-brittle transition; Evolution; Grain refinement; Grain size; Graphene; Graphite; Magnesium alloys; Magnesium base alloys; Mechanical properties; Microparticles; Microstructure; Nano-composite; Nanocomposites; Nanoparticles; Particulate composites; Tensile properties; Thermomechanical processing; Ultimate tensile strength
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2019.152231

In the present work, microstructural evolution and mechanical properties of a frictionally stir processed magnesium alloy reinforced with micro and nanoparticles were comprehensively investigated. Microstructural characterizations after the first deformation pass for both composites just implied a limited grain refinement along with the agglomeration/clustering of particles, and the difference between two composites was ignorable. While, deformation up to three FSP passes astonishingly followed a different trend, relative to the first pass. Achievement of a fine and homogenous microstructure in conjunction with the evolution of well-distributed particles and almost no sign of clusters were the outcomes of the third pass. Particularly, for the nanocomposite, a fine grain size of 2.29 μm is achieved. Additionally, better mechanical properties including higher values of Vickers microhardness and yield and also ultimate tensile strengths were attained after the third pass, compared to the first one. Better distribution of nanoparticles and their decisive role in improving tensile properties, compared to microparticles, led to the achievement of high hardness of 83 HV and ultimate tensile strength of 192 MPa for the graphene nanocomposite. Furthermore, the change from a brittle fracture to the brittle-ductile and ductile fracture is observed for micro and nanoparticles after the third FSP pass. [Display omitted] •Fabrication of metal matric composites through friction stir processing.•Homogenous and well-distribution of nano-graphene and micro-graphite particles.•The pinning effect of nano particles and achievement of ultrafine microstructures.•Remarkably improvement of the mechanical properties for both composites.•Brittle fracture of first pass processed specimen changes to mixed mode at third pass.