Protocols for repair and recycling of composites are described. Future developments that embrace self-healing systems are also considered. End-of-life options such as fibre and matrix recovery are also discussed. The economics of differing approaches are briefly considered using a whole-life cost model.

In this chapter the micromechanics of unidirectional fibre composites (see Section 5.1) are extended to laminates, where strain transfer occurs at a matrix crack other than at a fibre-break. The stress distribution under load is also discussed to describe the accumulation of damage under differing loading conditions.

Since the discovery of carbon fibres in the 1960s, the applications have grown. Because of the high specific strength and stiffness, aerospace applications have dominated, especially initially in military aircraft. The intent here is to demonstrate how the choice of material has been identified. Most critical demonstrators have come from the field of aerospace because of the benefits of carbon fibres and the development of confidence in their use in safety-critical designs. The latter has involved much testing and durability studies. Middleton has provided several case histories detailing the development of composite applications in aircraft structures [1]. The use of composite components has increased with improved confidence in the durability and reliability of these materials and structures. The Airbus A380 was introduced in 2006 using a carbon-fibre-reinforced polymer (CFRP) centre wing box, while the fuselage employed an aluminium–glass fibre composite laminate (GLARE). The centre wing box is a critical carbon-fibre composite structure that joins the wings to the fuselage. Together with several other composite components, such as the horizontal and vertical stabilizers, keel beam, and pressure bulkhead, the total composite usage is 22% w/w. In 2011 the Boeing 787 Dreamliner employed carbon-fibre materials for the fuselage and wings. In total, the latter used 80–90% by volume or 50% by weight of composite materials. The Airbus A350, introduced in 2015, also uses CFRP for the fuselage and wings, and in total composite usage is 53% w/w.

This chapter describes the mechanical performance of a fibre composite. A number of variables that control deformation and fracture are discussed: continuous or discontinuous fibres; fibre angle; fibre length; the transfer of stress between matrix and fibre at a short fibre and/or a fibre-break; and the role of the matrix. Individual components can fracture independently and control the micromechanics; the redistribution of stress after these events is discussed.

Using our strict definition of Atomic Scale Analytical Tomography (ASAT), we explore the current landscape of materials characterization tools and discuss how electron microscopy, field ion microscopy, and atom probe tomography are each approaching ASAT. State-of-the-art electron microscopy can achieve sub-angstrom spatial resolution imaging in 2-D and small volumes in 3-D but lacks single-atom chemical sensitivity, especially in 3-D. Field Ion Microscopy can achieve 3-D imaging on small volumes but not for all materials. Atom probe tomography can achieve single-atom elemental quantification in 3-D but lacks the spatial resolution necessary for ASAT. The chapter concludes with a comparison of the different techniques and discusses how different techniques may be complementary.

The historical backdrop for the role of microscopy in the development of human knowledge is reviewed. Atomic-scale investigations are a logical step in a natural progression of increasingly more powerful microscopies. A brief outline of the concept of atomic-scale analytical tomography (ASAT) is given, and its implications for science and technology are anticipated. The intersection of ASAT with advanced computational materials engineering is explored. The chapter concludes with a look toward a future where ASAT will become common.

We discuss how ASAT has the potential to make important advances on critical frontiers in crystallography. These key frontiers include unequivocal quantification of the nearest-neighbour relationships in materials, compositional information, and details of the degree of both short-range order and long-range order. Interfaces represent a particular opportunity. We discuss the present challenges in experimental microscopy-based methods to incorporate both the structural crystallographic information at crystal interfaces with the local chemical compositional information. We anticipate that ASAT will drive forward the field of interface science and interface engineering.

We conclude our contribution with a prospective and optimistic look to the art of what might be possible with the advent of ASAT. We see a convergence between the digital or computational world and the experimental, and envisage ASAT as an enabler for the design and development of new materials. This potential arises because real-world 3D atomic-scale information will bring direct insights into thermodynamic, kinetic, and engineering properties. Moreover, when coupled with machine learning and other computational techniques, it may be envisaged that discovery-based procedures could follow that adjust the observed real-world atomistic configurations toward configurations that exhibit the desired engineering properties. This will fundamentally change the role of microscopy from a tool that provides inference to a materials behaviour to one that provides a quantitative assessment. This opens the pathway to atomic-scale materials informatics.

A complete, albeit brief review of the history of atoms and atomic-scale microscopy is offered. From the concept of the atom developed by Greek philosophers to the ultimate microscopy, the path of development is examined. Atomic-Scale Analytical Tomography (ASAT) is cited as the ultimate microscopy in the sense that the objects, atoms, are the smallest building blocks of nature. The concept of atoms developed as the scientific method grew in application and sophistication beginning in the Middle Ages. The first images of atoms were finally obtained in the mid-twentieth century. Early field ion microscopy evolved eventually into three-dimensional atom probe tomography. The crucial role of the electron microscope in atomic-scale microscopy is examined. Recently, combining atom probe tomography and electron microscopy has emerged as a path toward ASAT. The chapter concludes with the point that ASAT can be expected in the next decade.