Glass forming ability and mechanical properties of misch metal-based bulk metallic glass matrix composite

Abstract

The effect of replacement of lanthanide by misch metal (Mm) in La-Al-TM (TM; transition metal, Ni, Cu and Co) alloys has been investigated to evaluate the possibility of fabrication of in-situ glass matrix composites with enhanced properties. For the as-cast cylindrical Mm(55)Al(25)Ni(10)Cu(10) alloy ingot with 3 mm diameter, the microstructure is consisted of two kinds of a few pin size crystalline phases (volume fraction: 4.6%) uniformly distributed in the metallic glass matrix. The substitution of La by Mm reduces the glass forming ability (GFA), i.e., lower the reduced glass transition temperature, T-rg (= T-g/T-L, where T-L is the liquidus temperature) and smaller superliquid temperature region, DeltaT(x) (= T-x - T-g, where, T-g is the glass transition temperature and T-x the onset temperatures of crystallization), enabling the fabrication of in-situ BMG matrix composite. The Mm(55)Al(25)Ni(10)Cu(10) metallic glass matrix composite sample exhibits the compressive fracture strength of 931 MPa, and in particular enhanced the compressive plastic strain of 1.2% before failure, The enhanced strength and ductility was explained by the presence of fine crystalline phases embedded in the BMG matrix, which led to a Multiple shear band formation.