Preparation Of Mg-based Bulk Metallic Glass Composites

In recent years, metallic glass has successfully applied in some areas, withimprovement of the technology related to it. However, the limited site of metallicglass due to its low glass-forming ability and the nature of brittleness have hinderedits wide and further application. In this paper, bulk metallic glass-BMG has beenprepared by the technique of hot press molding. The compatibility of the BMGgreatly increases compared to that of its crystalline counterpart, which is attributed tometallic glass’s softening behavior when heated the temperature of supercooled liquidregion. Furthermore, Mg-based BMG/Graphene composite has been synthesized inthe same principle. This paper includes the main aspects of work as following:(1) In this paper，for the molding method，material as selected object should havehigh glass-forming-ability（GFA）and wide supercooled liquid region felling in lowtemperature range． Therefore， in the present work， Mg-based metallic glassMg65Cu25Gd10is selected for peparing BMG/Grsphene composite，of which glasstransform temperature（Tg）and crystallization temperature（Tx）are413K and467K，respectively，supercooled liquid region is54K（ΔT=Tx-Tg=54K）(2) For determining thermal stability of Mg-based metallic glass, itscrystallization Kinetics has been investigated by the means of Non-isothermal andisothermal Differential Scanning Calorimetry(DSC). From further Kissinger andJohnson-Mehl-Avrami (J-M-A) analysis, it is showed that the metallic glass is stableat a relatively wide temperature region, which is validated by the remainedamorphous structure of bulk sample prepared by the technique of hot press molding.And the apparent activation energy, Avrami exponent, extrapolated incubation timeand crystallization time are induced, which is important for determining adequatetechnique parameters of hot press molding avoiding crystallization of Mg-basedmetallic glass powder.(3) In this paper, the process of hot press molding for the Mg-based metallicglass in the supercooled liquid region has been researched. Speciffically, basing on the thermodynamic parameters of the glass, the author explored the effects ofdifferent technique parameters of hot press molding including the changes in time andtemperature on the structure of Mg-based BMG/Graphene synthesized by hot pressmolding.(4) The preparing process and structure of Mg-based BMG/Graphenecomposites were also investigated in this paper. In the composite process it is theKey technique affecting the composite material that graphene is dispersedefficiencilly. The amount of grapheme added to Mg-based metallic glass.powder wassearched by real experiment in this paper.