Hits:

Indexed by:期刊论文

Date of Publication:2017-09-17

Journal:MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

Included Journals:Scopus、SCIE、EI

Volume:704

Page Number:45-56

ISSN No.:0921-5093

Key Words:Transition metal silicide; Morphology; Strength; Ductility

Abstract:The crystal growth and morphology evolution of D8(8) transition metal silicide and its influence on the mechanical properties of alloys have yet to be determined. In this paper, the effect of in situ-formed D8(8) (Mn, Fe)(5)Si-3 phase on the mechanical and wear performances of brasses is presented. By means of deep etching and phase extraction technologies, the morphology of (Mn, Fe)(5)Si-3 phase is found to exhibit long hexagonal prism, due to the higher growth velocity in the < 0001 > direction than that of < 11 (2) over bar 0 > according to the Mn-Si bond chain arrangement. Two kinds of hollows, i.e. internal hollow and prism facet hollow, are formed on the coarse primary (Mn, Fe)(5)Si-3 prisms, which can be ascribed to the restrained solute diffusion within the prism and attachment limited kinetics on the prism facet, respectively. With Increasing the (Mn, Fe)(5)Si-3 content, the hardness and yield strength increase effectively, which mainly results from the load transferring effect and grain refinement, supported by the good agreement between calculated and experimental results. The fracture mode transforms from ductile failure to quasi-cleavage and cleavage failure. Severe cracking tendency of high aspect ratio primary (Mn, Fe)(5)Si-3 particles containing large-sized hollows leads to slight increment in ultimate tensile strength and great ductility decrease at high (Mn, Fe)(5)Si-3 content. In addition, the fine eutectic (Mn, Fe)(5)Si-3 particles are beneficial to improve the ductility by acting as effective barriers to crack cleavage and void growth. The proper combination of thinner primary and eutectic (Mn, Fe)(5)Si-3 particles is found to efficiently restrain the crack creation and result in a good wear resistance. This study may be helpful to design high performance alloys reinforced with transition metal silicides by tailoring their morphology.