Creep behaviour of ODS aluminium reinforced by silicon carbide particulates: ODS Al–30SiCp composite

Creep Properties in TiO2 Nanoparticle Reinforced Aluminum Matrix Composites

“…[21] It has been pointed out that for Al alloys and their composites the true stress exponent n 0 is usually selected as 3, 5, and 8: (i) n 0 ¼ 3 for creep controlled by viscous glide processes of dislocation, (ii) n 0 ¼ 5 for creep controlled by high temperature dislocation climb (lattice diffusion), and (iii) n 0 ¼ 8 for lattice diffusioncontrolled creep with an invariant substructure. [23] The rational explanations for the high threshold stress in the particle reinforced composite have been well documented: [24,25] (1) Orowan bowing of dislocations, (2) internal back stress associated with dislocation climb, (3) attractive force between dislocations and particles. The linear regression analysis showed that the true stress exponent of minimum creep strain rate of 5 should be taken and Figure 4a shows the plots of _ e 1=5 against s in double linear coordinates.…”

Artificial neural network modeling of creep behavior in a rotating composite disc

“…Mishra and Pandey (1990), Pandey et al (1992, 1994) and Gonzalez and Sherby (1993) have used a true stress exponent of 8 for 6061 Al‐SiC P,W (subscript “P” for particle and “W” for whisker), SiC/Al and (TiB 2 ) P /Al composites, respectively. However, other research groups (Park et al , 1990; Mohamed et al , 1992; Park and Mohamed, 1995; Cadek et al , 1995, 1998; Li and Mohamed, 1997; Li and Langdon, 1997, 1999) have observed that a stress exponent of ∼5 or ∼3, rather than 8, provides a better description for the creep data of discontinuous SiC/Al.…”

“…However, the application of Norton's law to describe creep behavior of aluminium based composites has been objected on the basis of high values of apparent stress exponent and apparent activation energy observed in these composites (Tjong and Ma, 2000). In order to rationalize the strong stress and temperature dependency of creep rate reported for discontinuously reinforced aluminium/aluminium alloy matrix composites, the concept of an effective stress has been used by several workers (Mishra and Pandey, 1990; Park et al , 1990; Mohamed et al , 1992; Pandey et al , 1992, 1994; Gonzalez and Sherby, 1993; Park and Mohamed, 1995; Cadek et al , 1995, 1998; Li and Mohamed, 1997; Li and Langdon, 1997, 1999; Tjong and Ma, 1999; Ma and Tjong, 1999, 2000, 2001) including Pandey et al (1992) who have studied steady state creep behavior of Al‐SiC P composites under uniaxial condition, in the temperature range between 623 K and 723 K for different particle sizes of 1.7, 14.5 and 45.9 μ m and with varying volume fraction of reinforcement. The creep rate, ε˙ , under a given stress, σ , is expressed as a power law equation of effective stress, ( σ − σ o ), similar to Sherby's law (Sherby et al , 1977) as: Equation 1 where A ′ is a structure dependent parameter, n is the true stress exponent, Q is the true activation energy, E is the temperature‐dependent Young's modulus, σ o is the threshold stress, R is the gas constant and T is the absolute temperature.…”

A new model for the description of creep behaviour of aluminium-based composites reinforced with nanosized particles

“…In the case of Al-based metal matrix composites, Equation (1) needed to be modified to describe the behaviour that was almost invariably observed experimentally, that is, a marked curvature of the strain rate vs stress curve, which, in double logarithmic coordinates, became almost vertical in the low stress regime. An example is clearly illustrated in Figure 1, which shows the minimum strain rate dependence on applied stress for an oxide-dispersion strengthened Al [17] (ODS-Al in the following) and for the corresponding composite reinforced with 30% of SiC particulate (ODS-Al-30%SiC) [18,19]. The third material is an oide dispersion strengthened Al-5%Mg alloy reinforced with 30%SiC (ODS-Al5Mg-30%SiC) [20].…”