Non destructive texture and residual stress analysis of advanced materials and alloys by X-ray and Neutron diffraction

Nowadays applications are pushing materials to their limits. More often they need not only an optimized microstructure but also to maximize their capability exploiting directional properties. This is done through texture, aligning the crystallographic domains along special directions where the application requires. If, in some cases we are looking for special textures, in many others materials should avoid residual stresses as they can compromise the mechanical properties leading to premature failures. An exception is when we need to prevent crack nucleation and growth from the surface by using compressive outer layers. Texture and residual stresses are so becoming more and more important, and diffraction is the leading technique to analyze them whenever is needed for quality control or material application research and development. In particular X-ray diffraction is used as a lab and quality control tool; but we have to remember that it is limited to only a small finite penetration depth. Instead neutron diffraction can be used for bulk and thick specimens, but obviously it is not an easy technique to have access to. We will show some new advancements in the technique and data analysis for texture and residual stresses by X-ray and neutron diffraction. In particular how the techniques are going toward the use of multi-, position sensitive and area detectors to speed up the measurements. This can be used profitably by the analysis through new global simulations/fitting methods to obtain at once all the informations we need. This has permitted to analyze new materials and applications where it was not possible before. Some example concerning traditional and advanced alloys will be shown on both X-ray and neutron diffraction both for texture and residual stresses, ranging from steel for mechanical applications, to titanium alloys. Some more examples for composites (metal-metal or ceramic-metal) and thin films will illustrate the applicability of the technique outside the metal and alloys field. One further example concern the applicability of the texture analysis to obtain information in the archeo-metallurgy field. Finally a complete example on how these analyses can be used and transferred to the design of a complex shape memory alloy (SMA) device is reported.