Study of the Microstructure and Ring Element Segregation Zone of Spray Deposited SiCp/7055Al

Abstract

Composites of 7055 aluminum (Al) matrix reinforced with SiC particles were prepared using the spray deposition method. The volume fraction of the phase reinforced with SiC particles was 17%. The effect of the introduction of SiC particles on the deposited microstructure and properties of the composites was studied in order to facilitate the follow-up study. The structure and element enrichment zone of spray-deposited SiCp/7055 Al matrix composites were studied by Optical Microscope (OM), X-ray diffraction (XRD), Scanning Electronic Microscopy (SEM) and Transmission electron microscopy (TEM). The results show that the reinforcement phases of the SiC particles were uniformly distributed on the macro and micro levels, and a few SiC particles were segregated into annular closed regions. C and Si on the surface of SiC particles diffused to the Al matrix. The distribution of the two elements was gradient weakening with SiC particles as the center, and the enrichment zones of Si, Mg and Cu formed in the middle of the closed annular area of a few SiC particles. The enrichment zones were mainly composed of alpha-Al, SiC, Al2CuMg, Al2Cu and MgZn2. AlCu and AlMgCu phase precipitate on the surface of the SiC particles, beside the particle boundary, and had the characteristics of preferred nucleation. They tended to grow at the edges and corners of SiC particles. It was observed that the formation of nanoparticles in the alloy had a pinning effect on dislocations. The different cooling rates of the SiC particles and the Al matrix led to different aluminum liquid particle sizes, ranging from 20 to 150 μm. In the region surrounded by SiC particles, the phenomenon of large particles extruding small particles was widespread. Tearing edges and cracks continued to propagate around the SiC particles, increasing their propagation journey and delaying the fracture of the materials.

A modified Johnson-Cook model for dynamic behavior of spray-deposition 17 vol.% SiCp/7055Al composites at high strain rates

“…Draw the stress-strain curve under the reference condition, and fit it with 2-order polynomial, as shown in figure 8. According to the coefficient of the fitted 2-order polynomial, the values of A , 1 and  e ln * plots as shown in figure 9, in which the mean average slopes of the regression lines is the value of C 1 =0. 23.…”

“…SiCp/Al composites have been extensively applied in the automobile, aerospace, defense industries and other industries for their prominent properties in both physical and mechanical performance (e.g., light-weight, high wear resistance, high stiffness, excellent strength, good thermal stability and low price) [1][2][3][4][5][6][7]. Among considerable additive manufacturing technologies, spray-deposition is considered an advanced production technology for forming fine structure and fabricating high density metallic components [1,[8][9][10].…”

“…However, existing researches mainly focus on mechanical properties, the interface effects on the mechanical properties and static deformation characteristics [14,15]. As a matter of fact, composite components are likely to experience dynamic impact loading in several applications, it is generally known that all materials exhibit different deformation characteristics under static and dynamic loading conditions [1,5]. Studying flow behaviors of SiCp/Al composites at high strain rates is critical to explain the dynamic characteristics of the material in their application [16].…”

Effect of CeO2 Content on Microstructure and Properties of SiCp/Al-Si Composites Prepared by Powder Metallurgy

“…SiCp has the characteristics of isotropy, low expansion coefficient, and high strength, which are ideal reinforcing materials for preparing metal matrix composites [ 3 , 4 ]. SiCp/Al-Si composites combine the advantages of SiC and Al-Si alloys in strength, expansion, and wear resistance [ 5 , 6 ]. Li et al [ 7 ] studied the effect of the SiCp orientation anisotropy on the tensile properties of spray-formed SiCp/Al-Si composites compared with that of the matrix alloy without reinforcement particles.…”

Effect of Er on Microstructure and Mechanical Properties of 5052 Aluminum Alloy with Big Width-To-Thickness Ratio

“…With the continuous innovation of aviation, aerospace and other high-techs, people have put forward higher and higher requirements for the performance of aluminum alloys in recent years [1][2][3]. Aluminum alloys are developing towards great strength, high toughness and excellent corrosion resistance, and alloying or micro-alloying is one of the most effective methods [4][5][6][7].…”