The absence of thermal expansion mismatch strengthening in nanostructured metal–matrix composites

Mechanical and tribological properties of self-lubricating metal matrix nanocomposites reinforced by carbon nanotubes (CNTs) and graphene – A review

“…Usually, the addition of nano particles refines grains or confines grain growth. CTE and modulus mismatch are considered to be negligible when compared with Orowan and grain refinement in many recent observations [4,23,26,27].…”

Ultrasound Assisted Casting of an AM60 Based Metal Matrix Nanocomposite, Its Properties, and Recyclability

“…These dislocations are created during cooling due to mismatch in the Coefficient of Thermal Expansion (CTE) between the matrix and that of the reinforcement. The strengthening contribution of CTE mismatch during cooling down from the casting temperature to room temperature can be calculated according to Equation (A5) in Appendix A [39,41], where β is considered to be 1.25 [41], ∆α is the difference between the CTE of the matrix (28.5 × 10 −6 K −1 ), and AlN-particles (4.5 × 10 −6 K −1 ), and ∆T is the difference between the processing temperature and tensile test temperature (room temperature). It needs to be mentioned that particles smaller than a critical diameter d * are not expected to contribute to CTE-strengthening.…”

“…CTE mismatch: The strengthening contribution of CTE mismatch during cooling down from the casting temperature to room temperature can be calculated according to Equation (A5) [39,41].…”

A quantitative understanding on the mechanical behaviors of carbon nanotube reinforced nano/ultrafine-grained composites

“…These stresses are large enough to cause plastic deformation and create dislocations on the close vicinity of second phases observed by experiments [36], which reduce quickly with increasing distance from the boundaries of interface regions [37]. According to the experimental observations [21] and the theoretical model [38] that the extent of GNDs is limited in a small distance around the reinforcement for matrix with small grain size. Thus the concept of GBAZ is adopted here to address the extent of the effect of thermal stresses.…”

“…Choi et al [20] found that the work hardening capacity of CNT-reinforced nano/ultrafine-grained MMCs is not seem to be greatly affected by the content of the reinforcement, and attributed the phenomenon to the fact that CNT is mostly situated at GBs. Vogt et al [21] observed that geometrically necessary dislocations (GNDs) induced by thermal mismatch are constrained to nanostructured interfacial layers in a bulk nano-grained MMC under different heat treatments and quenching conditions, and the absence of thermal mismatch strengthening on the strength improvement of the composites is presented.…”