Abstract
The elastic properties of both linearly and non-linearly elastic metallic materials have often been approximated as constants, even though the non-linear elastic behaviours are unclear. Correspondingly, these properties are obtained through conventional characterisation techniques and require the physical fabrication of the materials. In recent years, the demands for novel metallic materials to satisfy engineering needs have increased. However, due to the sheer number of metal elements and the enormous permutation of their constituents in the metallic compounds, it is challenging to identify, fabricate, and characterise all these materials. Furthermore, it is tedious to control the purities, defect concentrations, phases, or crystalline structures of the metallic compounds. Lately, the availability of density functional theory (DFT) has enabled a more practical means to synthesize and characterise these materials using computational simulations. The evolvement in its algorithms has also improved its accuracy and reliability in duplicating the properties of existing materials, and its usage continues to extend the fringe of scientific discoveries. This research aims to reveal the influences of multi-doping and straining on the properties of intrinsically brittle bulk D022-TiAl3 intermetallic compound by utilising DFT simulations, and to understand the mechanisms involved in the brittle-to-ductile transitions. This investigation is important as the current techniques to improve the ductility of D022-TiAl3 remain unsatisfactory and unable to approach the same ductility as its metastable L12-TiAl3 counterpart. Additionally, this research investigates the mechano-wetting effects on metallic surfaces and develops a technique to engineer surface wettability that can disrupt the strong water-energy dependency in their productions. The results reveal that dopants can redistribute the electrons density in D022-TiAl3 to form new localised strong covalent bonding, and correspondingly weaken the surrounding strong Ti-Al interactions to improve its overall ductility. When the intermetallic compounds are doped 4 with defects, which resulted in biaxial straining intrinsically, their ductility was found to be better than L12-TiAl3. Further analysis using the Lennard-Jones model reveals Young’s modulus to be a function of strain and this relationship offer an alternate explanation on the mechanism of brittle-to-ductile transition in the ductile mode cutting of brittle materials. This relationship also helps to derive a new mechano-wetting model that relates surface wetting changes to a third-degree polynomial function of strain. A new mechano-wetting technique was introduced for engineering applications, and a proof of concept to improve water collection from moist air is demonstrated in a fog-harvesting experiment.