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The Manufacturing of Magnesium Degradable Biomedical Implants
Published in Savaş Kaya, Sasikumar Yesudass, Srinivasan Arthanari, Sivakumar Bose, Goncagül Serdaroğlu, Materials Development and Processing for Biomedical Applications, 2022
Lifei Wang, Pengbin Lu, Qiang Zhang, Liangliang Xue, Xiaohuan Pan, Hua Chai, Srinivasan Arthanari, Maurizio Vedani
Ge et al.[37,38] successfully fabricated the thin-wall tube on ZM21 Mg alloy through hot direct extrusion in one step. Before extrusion, severe plasticity deformation (SPD) was conducted. As well known, grain refinement is an efficient method to enhance the mechanical property, not only strength but also ductility. Especially, the grain boundary sliding (GBS) can be activated so that the ductility is improved and super-plasticity may be achieved when the grains are refined to a critical value.[39–41] In the research of Ge et al.,[37,38] the relatively low-temperature ECAP process (200 °C for 8 passes then 150 °C for 4 passes) was conducted first. Compared with the initial ZM21 alloy, the grains were refined (0.52 μm) and the YS was also improved to 340 MPa. Then the ultra-fine-grained (UFG) Mg billets were used to produce mini-tubes with an outer diameter of 4 mm through a hot extrusion process (temperature range from 150 °C to 300 °C). The thin-wall tube was successfully obtained even at 150 °C due to GBS, and also no grain coarsening happened. Successively, the outer diameter of the tube was reduced to 2.4 mm and the thickness was about 0.4 mm.
Magnesium Metal Matrix Composites for Biomedical Applications
Published in S. M. Sapuan, Y. Nukman, N. A. Abu Osman, R. A. Ilyas, Composites in Biomedical Applications, 2020
Notably affecting corrosion resistance, the microstructure evolution of magnesium composites is the grain size, grain boundary, and phase distribution. Grain refinement leads to transform the density of grain boundaries and increases the mechanical properties as well as the corrosion resistance. Studies revealed the fraction of primary and secondary phases, and grain sizes are the key factors that control corrosion resistance. In metal matrix composites, the base matrix metal has a grain structure that can be refined and reformed to increase the properties of the composite material. Reinforcement is introduced in the metal matrix, which effects grain boundaries based on their shape and size. The size of the reinforcement is decreased, which will increase the grain refinement; whenever grain refinement is done the properties of the composite material increase. A sample with the smallest grain size and largest fraction of secondary phase improves the corrosion resistance because of the secondary phase, which affects galvanic corrosion and suppresses influence of grain size.
Grain Boundary Characteristics in Polycrystalline Materials
Published in Jeffrey P. Simmons, Lawrence F. Drummy, Charles A. Bouman, Marc De Graef, Statistical Methods for Materials Science, 2019
Hossein Beladi, Gregory S. Rohrer
There is an ongoing drive among research groups around the world to develop novel materials to meet the growing need for higher performance at lower cost. A major strategy to achieve this goal is to engineer the microstructure constituents of polycrystalline materials according to their contributions to the particular property of interest. Polycrystalline materials can be thought of as composite structures consisting of grain interiors and grain boundary regions, where two grains are joined. The grain size is not a sufficient factor to evaluate the polycrystalline mechanical property, as grain refinement may or may not lead to increased strength [1131]. In addition, the grain size only provides limited information about the grain boundary (i.e., density and spacing) rather than the types of grain boundaries and their characteristics.
The capability of coupled fuzzy logic and adaptive neural network in the formability prediction of steel sheets
Published in Waves in Random and Complex Media, 2023
Xiao Chen, Linyuan Fan, Dandan Ji, Peng Lin
In recent years, the effects of the microstructure of sheet material on the forming limit and behavior have been investigated [28,29]. Amelirad and Assempour [5] employed the crystal plasticity method to study the influence of grain size on the forming limits of 304L steel sheets. They modeled semi-real grain shapes in their simulations to obtain necking points in various loading paths. The effect of texture on the forming limits has been the subject of both experimental and theoretical research studies. Xu et al. [30] investigated grain size effects on the forming limits of copper sheets. They concluded that extra-large grain size results in a drop in forming limits. Azghandi et al. [31] studied the effects of the grain refinement of magnesium alloy AZ31 on the ductility and forming limits. They experimentally showed that grain refinement enhanced the ductility of the material while forming limits demonstrated small dependence on the grain sizes. In Yamaguchi and Mellor, an increase in thickness to grain size was shown to have a detrimental effect on the limited strains of sheets [32].
Recent progress on microstructure manipulation of aluminium alloys manufactured via laser powder bed fusion
Published in Virtual and Physical Prototyping, 2023
Zhen Xiao, Wenhui Yu, Hongxun Fu, Yaoji Deng, Yongling Wu, Hongyu Zheng
In summary, growing attention has been drawn to the uptake of LPBF for the fabrication of aluminium alloys. The thermal dynamics of LPBF allows rapid melting and solidifying of powder materials and the subsequent intrinsic heat treatment. Typical microstructure includes columnar grains along the building direction and strong crystallographic texture, which results in anisotropy in the mechanical properties of the parts. Grain refinement resulting in more fraction of equiaxed grains favour the mechanical performance. For aluminium alloys with low strength, the major study on near eutectic Al–Si alloys with good printability was focused on processing parameters previously. Recently growing number of studies were performed on the columnar to equiaxed transition to achieve high UTS and isotropy. Grain refining by inoculants, the introduction of reinforced aluminium matrix composite, and alloying with Ni and Cu elements were explored. For moderate strength Al–Mg alloys, solidification crack was mainly eliminated by Sc and/or Zr alloying. A bimodal microstructure was reported and tailored by parameter manipulation. For high strength Al–Cu and Al–Zn–Mg alloys, three approaches were attempted to refine the grain and improve the feasibility of LPBF: (1) optimising parameters by extremely high or low energy input, substrate preheating and supportive structure construction; (2) narrowing down the freezing range; (3) inoculants treatments.
Corrosion resistance of fine-grained rebar in mortars designed for high-speed railway construction
Published in European Journal of Environmental and Civil Engineering, 2018
Jinjie Shi, Guoqing Geng, Jing Ming
For many metallic materials, grain refinement is a well-established method to increase strength without sacrificing ductility (Ralston & Birbilis, 2010). The influence of grain size on corrosion performance has been investigated extensively in previous studies (Afshari & Dehghanian, 2009; Aung & Zhou, 2010; Chen, Wang, Jiang, & Li, 2005; Di Schino, Barteri, & Kenny, 2003; Di Schino & Kenny, 2002; Hadzima, Janeček, Estrin, & Kim, 2007; Li, Wang, & Liu, 2004; López, Cisneros, Mancha, García, & Pérez, 2006; Luo, Xu, Wang, Shi, & Yan, 2010; Mishra & Balasubramaniam, 2004; Pisarek, Kędzierzawski, Janik-Czachor, & Kurzydłowski, 2009; Pisarek, Kędzierzawski, Płociński, Janik-Czachor, & Kurzydłowski, 2008; Ralston & Birbilis, 2010; Ralston, Birbilis, & Davies, 2010; Shi, Sun, & Geng, 2011; Shi, Sun, Geng, & Jiang, 2011; Wei, Dong, & Ke, 2010). However, ambivalent conclusions were drawn on ferrous alloys (steel and rebar) (Ralston & Birbilis, 2010; Ralston et al., 2010). It was reported that FG structure is more corrosion-resistant in the presence of compact oxide film on material surface. However, in the absence of such film, higher grain boundary densities seem to increase the corrosion rate as the overall surface reactivity is higher (Ralston et al., 2010).