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Borides; Density (specific gravity); Ductility; Elastic moduli; Metallic matrix composites; Microstructure; Molybdenum; Niobium; Steel; Stiffness; Tantalum; Tensile strength; Tungsten; Zirconium, Combinatorial screenings; Lightweight design; Mechanical and physical properties; Mechanical performance; Micro-structural properties; Spherical morphologies; Strength; Strength and ductilities, Alloy steel
Abstract:
We systematically screened the mechanical, physical and microstructural properties of the alloy systems Fe–10 B–5 X (at.; X = Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W), in order to identify novel metal matrix composite steels as next generation lightweight materials. The alloys were synthesised and processed by bulk liquid metallurgical techniques, and subsequently analysed for their mechanical and physical properties (i.e. Young's modulus, density, tensile strength and ductility) as well their microstructure and constitution. From the wide variety of observed boride phases and microstructures and resultant different properties, Cr and Zr additions were found to be most effective. Cr qualifies well as the high fraction of M2B borides of spherical morphology allows achieving a similar stiffness/density ratio and mechanical performance as the reference Ti alloyed materials, but at substantially reduced alloy costs. Zr blended composites on the other hand are softer and less ductile, but the alignment of spiky ZrB2 particles during swaging led to a much higher – though most probably anisotropic – specific modulus. Consequences and recommendations for future alloy and processing design are outlined and discussed. © 2016 Elsevier Ltd
