Bulk Nanostructured Multicomponent Alloys

The preparation of Ti 50 Cu 28 Ni 15 Sn 7 metallic glass composite powders was accomplished by mechanical alloying of pure Ti, Cu, Ni, Sn and WC for 18 ks. In the ball-milled composites, initial WC particles were homogeneously dispersed in the Ti-based alloy glassy matrix. The metallic glass composite powders exhibited a large supercooled liquid region just below the crystallization temperature. The presence of WC nanoparticles did not change the glass formation ability of amorphous Ti 50 Cu 28 Ni 15 Sn 7 powders. The as-milled Ti 50 Cu 28 Ni 15 Sn 7 and composite powders were consolidated by vacuum hot pressing into compact discs with a diameter and thickness of 10 and 4 mm, respectively. Microstructural analysis showed that the bulk metallic glass composite contained submicron WC particles homogeneously embedded in a highly dense nanocrystalline/amorphous matrix. Incorporation of WC into consolidated composite compacts resulted in a significant increase in hardness.

Section: Resultsmentioning

confidence: 93%

Synthesis of Ti-Based Bulk Metallic Glass Composites Containing WC Particles

Jeng

Lee

2005

“…[17][18][19] However, when the volume fraction of crystallized phases exceeds a critical volume fraction of roughly 40%, the crystallized alloy exhibit decreased yield strength and brittle failure. For the asfabricated Ti 66 Nb 13 Cu 8 Ni 6:8 Al 6:2 bulk alloys with and without WC addition in our case, the precipitated -Ti is a ductile phase and the other precipitated phases are brittle phases.…”

Section: Resultsmentioning

confidence: 99%

“…Therefore, the same variation of the volume fraction of precipitated brittle phases as in the Refs. [17][18][19] leads to the variation of yield strength and fracture strain for the as-fabricated bulk alloys with different WC addition.…”

Section: Resultsmentioning

confidence: 99%

Microstructure and Mechanical Properties of SPSed (Spark Plasma Sintered) Ti66Nb13Cu8Ni6.8Al6.2 Bulk Alloys with and without WC Addition

Chao

Chen

et al. 2009

Ti 66 Nb 13 Cu 8 Ni 6:8 Al 6:2 bulk alloys with and without WC addition were fabricated by spark plasma sintering and crystallization of amorphous phase. Microstructure analysis indicates that Ti 66 Nb 13 Cu 8 Ni 6:8 Al 6:2 bulk alloy without WC addition has a ultrafine-grained microstructure with in situ precipitated ductile -Ti(Nb) phase, composed of soft (Cu, Ni)-Ti 2 regions surrounded by hard -Ti regions. The alloy exhibits high fracture strength of above 2000 MPa and remarkable plasticity of $21%. In contrast, Ti 66 Nb 13 Cu 8 Ni 6:8 Al 6:2 bulk alloys with WC addition consist of a microstructure of in situ precipitated ductile -Ti regions surrounded by a mixed phase regions of (Cu, Ni)-Ti 2 , TiC, WC and residual glassy phase. The alloys with WC addition display brittle facture behavior. The different plastic deformability for the fabricated bulk alloys with and without WC addition can be explained based on their distinctive microstructures.

“…The crystalline phase dispersed uniformly in the amorphous matrix may act as an obstacle for inhibiting the shear band propagation, resulting in the multiple shear band formation throughout the specimen, which, in turn, leads to the enhanced plasticity. 12,13) BMG matrix composites can be obtained by various ways such as partial devitrification of as-cast metallic glasses, mechanical alloying of elemental powders blended with insoluble particles, and precipitation of a dendritic crystalline phase from the melt during casting. [13][14][15][16][17] In this study, we intended to fabricate a Cu-based BMG matrix composite with improved ductility.…”

Section: Introductionmentioning

confidence: 99%

Formation of Ductile Cu-Based Bulk Metallic Glass Matrix Composite by Ta Addition

Kim

Lee

2003

The Effect of the Ta addition on the fabrication of the ductile phase reinforced Cu-Zr-Ti bulk metallic glass (BMG) matrix composite was investigated. A composite microstructure consisted of mm-scale Ta-rich solid solution particles distributed in the BMG matrix was successfully obtained by injection casting of the (Cu 60 Zr 30 Ti 10 ) 95 Ta 5 alloy into a copper mold. Ta-rich solid solution particles were observed to form first in the liquid melt during solidification, while the remaining melt solidified into the amorphous phase at lower temperature. The monolithic Cu 60 Zr 30 Ti 10 BMG shows a compressive strength of 2080 MPa and a fracture strain of 3.3%, while the (Cu 60 Zr 30 Ti 10 ) 95 Ta 5 BMG matrix composite shows compressive strength of 2320 MPa and, in particular, a significantly improved plastic strain to failure of about 14.5%. The remarkable ductility improvement in the (Cu 60 Zr 30 Ti 10 ) 95 Ta 5 composite could be explained by the presence of the highly ductile Ta-rich particles.