Search

A design map in regard to the generalized-stacking fault (GSF) energy is plotted for Ti 5 Si 3 (Ti 60 Si 36 ) alloying with 12 ternary elements in { 1 1 ¯ 00 } [ 0001 ] slip system. Hereinto, alloying elements occupy preferable Ti sites near slip planes. The elements with a larger radius difference from Ti tend to reduce the GSF energies more dramatically. Moreover, the elements smaller than Ti are more prone to decreasing GSF energies than those larger than Ti. Accordingly, the addition of ternary elements, like Ni, Cu and Co, will lead to an obvious decrease in GSF energies by 18.0%, 16.7% and 13.4% respectively, and therefore may facilitate the initiation of prismatic stacking faults and furthermore enhance ductility. Note that the decline of GSF energies is attributed to the weakening covalent bonds between slip planes with the introduction of ternary elements. Our calculations provide a guide to experiments on the design of Ti 5 Si 3 compounds with tailored properties. [ABSTRACT FROM AUTHOR]

Abstract: The electronic, elastic and mechanical properties of eight binary B 2 – type intermetallic compounds of Ag and Au (AgX and AuX, X=Mg, Sc, Zn and Cd) have been studied systematically using first principles density functional theory within generalized gradient approximation. Ground state properties such as lattice constant (a 0), bulk modulus (B), its pressure derivative (B′) and elastic constants are calculated. The present results are in good agreement with the experimental and other available theoretical results. Poisson’s ratio (σ), Young’s moduli (E), shear moduli (GH ) and the ratio of elastic anisotropy factor (A) are also estimated. Ductility for these compounds is further analysed by calculating the ratio of B/GH and Cauchy pressure (C 12–C 44). Amongst all the intermetallics AuZn is found to be most ductile due to the presence of strong metallic bonding, and AgZn is least ductile in all the Au and Ag intermetallic compounds. [Copyright &y& Elsevier]