Structure, Properties, and Processing of Two-Phase Crystalline-Glassy W- base Alloys

摘要

Amorphous or glassy metals are a unique class of materials that typically exbibit higher strengths than their crystalline counterparts but have limited ductility. Mechanical alloying (MA) of metal powders offers the possibility of forming metallic glasses for a large range of systems. Unfortunately, consolidation of the powder to bulk form usually results in crystallization of the amorphous phase. Previous research has shown that MA can produce a W-Ni-Fe amorphous powder with remnant nanocrystalline W particles in the glassy matrix. The goal of this research was to consolidate mechanically alloyed W-Ni-Fe powders to near or full density without causing crystallization of the W-Ni-Fe glassy phase. A systematic study on the consolidation of the most thermally stable alloy was conducted using different consolidation techniques and binder materials. Experiments were designed to examine the effects of different processing parameWrs including: temperature, pressure, time, and binder amount. The experimental results showed that it was possible to consolidate the MA W-Ni-Fe to a calculated density of 98 to 99% while retaining the glassy/amorphous structure. The process involved MA elemental Cu powder with the MA W-Ni-Fe powder and consolidating the composiW powder by Rapid Sinter Forging (RSF). Pressure was identified as the dominant processing parameter for densification. Temperature's effect on densification was minimal but important for crystallization of the glass.