Preparation And Performance Of In-siut TiC Particles-Dendrite Bulk Amorphous Composites

Zr-base metallic glasses, especially Zr–Ni-Al system have attracted widely attention by material scientists, because of its high amorphous formation ability and good mechanical properties such as high compressive strength and hardness.And through the study of amorphous formation ability and mechanical properties of Zr-base metallic glasses recent years, material scientists have moved on to Zr-base metallic glass matrix composites for seeking a way to solve brittle fracture problem of Zr-base metallic glasses.They find out a lot systems of metallic glass matrix composites, and the particles reinforced Zr-base metallic glass matrix composites materials is an important one. In this paper, TiC particulate induced crystallization dendrite-particulate reinforced Zr-matrix amorphous composites were fabricated by using vacuum furnace and copper mold casting techniques. Glass forming ability, thermodynamics action and dendrites phase formation were investigated by using XRD diffractometer, DTA analysis and SEM analysis.The Zr₅₃Al₂₃Ni₂₄ amorphous composite cylinder(4 mm diameter, 80 mm length) which add of in-situ synthesis of TiC with the mass fraction respectively 0wt%,0.5wt%, 0.7wt%,1.3wt%,1.7wt%,2.0wt% and 2.3wt% and the Cu_23.1Zr_60.5Al_16.4 amorphous composite with the mass fraction 1.3% were prepared by copper mold casting techiques process. Through the SEM and XRD analysis found there are little crystallized phases with the increase of TiC particle, while the mass fraction is 1.3% can prepare the particles-dendrites enhancement of Zr-matrix amorphous composites and the dendrites uniform distribution. Combined with phase diagram can identify the dendrites as AlZr₂ and AlZr₃ by XRD analysis. When the content of TiC particles is 1.7wt%, can be observed uniform distribution of micro-droplet grains by SEM.Through nonisothermal crystallized research of the DTA analysis for samples which content of TiC particles 0.0wt% and 1.3wt% shows that: the crystallization curve of the quaternary system was significantly different. The effective activation energies for the crystallization of the bulk metallic glass matrix composites were evaluated by Kissinger and Ozawa equation. The results show that the crystallization process of six kinds of bulk metallic glass matrix composites can be regarded as a kinetically modified thermodynamic phase transformation process. The samples content of TiC particles 0.0wt% and 1.3wt% have the higher effective activation energy for the crystallization temperature and the highest thermal stability. The maximum GFA appears at Zr–Ni-Al system with 1.3wt% TiC particles, with characteristic thermal parameters of Tg =463.1°C, Tx=531.7°C ,â–³Tx= Tx-Tg = 68.6°C andγ= 0.524. And characteristic thermal parameters are Tg =499.7°C, Tx=548.4°C ,â–³T x= Tx-Tg = 48.7°C ,when Zr–Ni-Al system contains with 1.3wt% TiC.Compare the structure between Zr₅₃Al₂₃Ni₂₄ and Cu_23.1Zr_60.5Al_16.4 amorphous composite with the mass fraction 1.3%, and because the existence of dendrite in Zr₅₃Al₂₃Ni₂₄ amorphous composite, the effect of thermal stress with DTA curve are obviously different. Because of the existence of dendrite, the thermal stress of particles affected DTA curve little. However, because there is no dendrite in the Cu_23.1Zr_60.5Al_16.4 amorphous composite and the thermal stress of particles bring into full effect of DTA curve, the DTA curve trend to have significant change.Based on the test of mechanical behaviour of metallic glass matrix composites, the experiment results show that: The metallic glass matrix composites with the addition of TiC possess the relatively higher intensity and Vickers hardness. At the same make the system show some of the plastic deformation and the Zr–Ni-Al system contain with 1.3wt% TiC shows higher intensity and hardness than bulk metallic glass and respectively improved 25.9% and 23.9%, show 1.24% ability of plastic deformation.Through mechanical tests showed: the Zr–Ni-Al system contains with 1.3wt% TiC is the best comprehensive performance one.