High Strain Rate Superplasticity of Aluminum-Based Composite Materials
High strain rate superplasticity (HSRS) is a promising route to overcome the intrinsic strength limitation and low workability of conventional aluminum alloys. Achieving high strain rate of aluminum alloy by using superplastic forming (SPF) technique above a certain temperature can provide a range of advantages such as weight reduction, increase of ductility and part complexity. The HSRS phenomenon usually occurs between 0.1-10/s strain rate in aluminum based composite material systems(ABCM).
HSRS of ABCM is greatly affected by interfacial properties which consists of both chemical composition and mechanical properties. Therefore, controlling and optimizing the the matrix/composite interfacial interaction by adding appropriate reinforcement layers will further enhanced the HSRS behaviour of such materials. Once a good interfacial contact between matrix and reinforcement layer is achieved, it will lead to significant enhancement of mechanical strength, strain rate sensitivity, toughness and wear resistance performance of ABCM.
However, extensive studies have been carried out to examine the effect of reinforcement layers and their interfacial interactions on HSRS of ABCM and related properties. Even though the results are promising, very few have been presented that have focused on finding optimal solutions for developing interfaces with desirable characteristics to influence HSRS performance. Furthermore, the level of understanding of the factors affecting HSRS of ABCM and their contributions remains elusive.
Therefore, there is a need to develop an optimized method to form interfacial layers for ABCMs which can enable them to demonstrate efficient HSRS performance. This work aims to understand the complex characteristics that determine HSRS of ABCM in order to achieve a better insight into the hierarchical structures of reinforcement layers. The proposed approach is expected to yield more consistent, optimized, and robust performances of ABCM with improved strain rate sensitivity.
The main objective of this work is to explore the influence of interfacial layer characteristics on strain rate sensitivity of ABCM. Several binary, ternary and quaternary systems consisting of core and reinforcement layers will be investigated. The incorporation of different matrix and reinforcement materials in the proposed systems will enable the exploration of varied interfacial attributes. The combination of different ratios of material will enable further investigation on HSRS behaviour when the ratio of matrix and reinforcement layers is altered.
Various physical, mechanical and chemical properties will be tested to confirm the formation of desired structures and interfaces. This will include investigations of the effects of heat treatments, laser treatments, and differing substrate materials on HSRS performance. Additionally, the thermal and surface properties of the interface between fragments of material will be investigated by atomic force microscopy (AFM) and scanning transmission electron microscopy (STEM).
The findings of this research are expected to provide an in-depth knowledge of factors influencing the HSRS performance of ABCM and ultimately the development of more efficient, reliable, and robust materials. This will be achieved by further investigating the effects of chemistry, size, structure, and surface of the interfacial layers on HSRS performance of aluminum-based composite materials and identifying optimal strategies for forming a desired interface. A preliminary study of HSRS behavior has been carried out to provide the direction and base on which the research can be built.
The outcome of this work will be highly beneficial in developing new material systems for high strain rate forming of materials which are light weight and cost effective. It is expected that the findings from this research will further the understanding of HSRS of ABCM and will translate into applications in aerospace and automotive industries.
