Hot deformation behaviour and processing maps of AA6061-10 vol.% SiC composite prepared by spark plasma sintering

Abstract

AA6061-10 vol.% SiC composite was successfully prepared by spark plasma sintering. The deformation behaviour of this composite was studied using the uniaxial compression test, which was conducted at temperatures between 300 and 500°C and strain rates between 0.001 and 1 s −1 . Results indicate that the stress-strain curves of the AA6061-10 vol.% SiC composite typically feature dynamic recrystallization. The steady stress can be described by a hyperbolic sine constitutive equation, and the activation energy of the composite is 230.88 kJ/mol. The processing map was established according to the dynamic materials model. The optimum hot deformation temperature is 450-500°C and the strain rate is 1-0.1 s −1 . The instability zones of flow behaviour can also be identified using the processing map.Al matrix composite, hot deformation, processing map, stress-strain curves, spark plasma sintering Citation:Li X P, Liu C Y, Sun X W, et al. Hot deformation behaviour and processing maps of AA6061-10 vol.% SiC composite prepared by spark plasma sintering. Sci China Tech Sci, 2016, 59: 980988,

Hot deformation behaviour of bimodal sized Al2O3/Al nanocomposites fabricated by spark plasma sintering

“…Hence, the combined effects of temperature and strain rate on deformation were analysed by constitutive equation through the Zener-Hollomon parameter (Z) in hyperbolic sine function. The effects of Z values on tensile properties, dynamic softening and also associated microstructural evolution during hot deformation were investigated by electron back scattered diffraction technique (EBSD) (Kang & Chan, 2004;Jiang et al, 2014;Li et al, 2016). Figure 2 presents the true stress-true strain curves of the bimodal sized Al 2 O 3 /Al nanocomposites at different strain rates and temperatures.…”

“…Additionally, the presence of nondeforming and hard Al 2 O 3 particles inside the aluminium matrix during hot deformation process leads to form a strain gradient in the matrix near the particles because of different level of deformation around the matrix and the particles. It follows that there is a heterogeneous disparity of strain in the matrix (Wang et al ., 2017; Sadeghi et al ., 2017b), The strain gradient creates a region of high dislocation density and large orientation gradient, which is called PDZ (Li et al ., 2016) Thus, the PDZ can be considered as an ideal site for development of a recrystallisation nucleus, and particles can promote the nucleation of DRX.…”

“…To probe the simultaneous effect of deformation temperature and strain rate, kinetic analyses should be considered to explore the role of activation energy, Z parameter and other important parameters on mechanical behaviour and microstructural properties of the bimodal sized Al 2 O 3 /Al nanocomposite. More generally, the deformation activation energy is an important physical and kinetic parameter indicating plastic deformability and qualitatively reflects the energy barrier to dislocation motion for metals, alloys as well as metal matrix nanocomposites (Li et al ., 2016; Wang et al ., 2017). In this end, it can be rationalised to expect a higher value of this energy signifying higher dragging forces to the movement of the dislocations in hot deformation processes (Sang et al ., 2016).…”

“…Interestingly, PAMNCs are considered as a group of advanced materials combining the good mechanical properties of Al and multifunctional properties of the ceramic reinforcements. PAMNCs combine the ductility and toughness of aluminium with the high strength and modulus of ceramics, leading to greater strength to shear and compression, and to higher service temperature capabilities (Ravichandran & Prasad, 1991; Li et al ., 2016; Wang et al ., 2017). However, higher volume fraction of the ceramic particulates restricts plastic flow of the matrix alloy, leading to poorer mechanical properties as a result of the higher porosity and more severe stress concentration.…”

“…Although the design of bimodal structure has successfully improved the overall mechanical performance of PAMNCs at room temperature (Sajjadi et al ., 2012; Cavaliere et al ., 2019). Besides, most done studies on PAMNCs relating to high‐temperature applications were concentrated on a unireinforced nanocomposite with matrix of Al alloy (Asgharzadeh & Simchi, 2008; Asgharzadeh et al ., 2011; Atrian et al ., 2015; Ezatpour et al ., 2015; Li et al ., 2016; Wang et al ., 2017). For instance, many researchers have reported that the addition of ceramic particles such as Al 2 O 3p increased the strength of aluminium at high temperatures and hence their thermal stability (Abouelmagd, 2004; Asgharzadeh et al ., 2011; Ezatpour et al ., 2015).…”