Aluminium metal matrix composites (AMMCs) are the fastest developing materials for structural applications due to their high specific weight, modulus, resistance to corrosion and wear, and high temperature strength. Carbon nanotubes (CNTs) is known as the material of the twenty-first century for its various applications in structural components for their high specific strength as well as functional materials for their exciting thermal and electrical characteristics. The present study comprise a systematic literature review of Al/CNT nanocomposites fabricated through a solid state friction stir processing. The present review is primarily focussed on the dispersion and survivability of CNTs in the Al matrix because these are the key factors in deciding the mechanical properties of the fabricated composite. Additionally, the formability, weldability and machinability of the FSPed fabricated composites reinforced with CNTs are also summarised here. Based on the detailed literature review, following research gaps are identified which require a critical and more focussed attention of the scientific community working in this research area: (i) the presence of agglomeration or clustering of CNTs in the composite, (ii) survivability and shortening of CNTs during FSP, (iii) interfacial reactions or the formation of reaction products (such as Al4C3) between Al matrix and CNTs, and (iv) the unidirectional alignment of CNTs in the fabricated composite. Important suggestions for further research in effective dispersion of CNTs with its preserved structure by FSP are also provided.

    Abstract
    1 Introduction
    2 Friction stir processing
        2.1 Advantages
        2.2 Applications
    3 AlCNT nanocomposite fabricated through FSP
    4 Formability
    5 Machinability
    6 Weldability
    7 Summary
    References

• Abhishek Sharma(Joining and Welding Research Institute, Osaka University)
• Gaurav Gupta(CSIR- Advanced Materials and Processes Research Institute)
• Jinu Paul(Department of Mechanical Engineering, Indian Institute of Technology, Department of Mechanical Engineering, National Institute of Technology)