Preparation Of Cu-based Bulk Metallic Glasses Composites With Mechanical Properties

In recent years,Cu-based metallic glasses especially Cu-Zr-Al system have attracted widely attention since its high strength,high hardness and excellent mechanical properties.However,there are also many questions and problems both in the theoretical and applying field of this kind alloys,for example,how to prepare the super-size BMG and reduce the requirements in preparing processes;how to improve their plastic.In this paper,we use magnetic levitation melting-copper mold suction casting equipment,a series of Cu36Zr48Al8Ag8 bulk metallic glasses were prepared by melt overcooling treatment. And the thermal behaviors, structure and mechanical properties of Cu-based metallic glasses were studied, found some Cu-based amorphous alloys with larger critical size,better mechanical properties and application potentials.The results obtained in this thesis may enrich the theories in Cu-based metallic glasses's fields and promote the application of this system in industry effectively.Cu36Zr48Al8Ag8 amorphous alloys with 3mm in diameter were prepared by semi-solid thermal insulation treatment,study its glass-forming ability and thermal stability. The results-showed that three kinds of specimens are as all amorphous alloy,there are crystal precipitation trend. Cu36Zr48Al8Ag8 supercooled liquid range with the extended holding time decreases, thermal stability decreased gradually. Reduced glass transition temperature Trg are at 0.60-0.65, so have a good glass forming ability.In the amorphous group of yuan and the formation of amorphous when the cooling rate under the same conditions, with the extension of soaking time, liquid crystal alloy tended to reduce the thermal stability,the atomic arrangement is also changed from dense to sparse, atomic between the free volume increases, its low level of compaction, hardness lower.The plastic phase crystallization of amorphous composite materials can improve the plasticity, we have done amorphous sample, with the holding time extended, and its plastic deformation is reduced, showing that our experiments may have produced brittle phase trend. Along with adding a small amount of Fe was prepared by (Cu0.36Zr0.48Al0.08Ag0.08)100-xFex(x=0,3,5) amorphous alloy sand this amorphous alloy is better than Cu36Zr48Al8Ag8 mechanical properties. And the hardness also increased significantly.Fe a large number of accession, an increase of alloy composition of the solid-liquid two-phase range, in the semi-solid suction casting process, contribute to the formation of compounds, and contribute to the formation of amorphous and crystal composite materials. (Cuo.36Zr0.48Al0.08Ag0.08)100-x Fex(x=10,15,20) alloy system, Fe a large number of the accession of Cu36Zr48Al8Ag8 alloy solid-liquid two-phase range increases, therefore, reduces the Cu36Zr48Al8Ag8 cold alloy system, the glass-forming ability, the promotion of crystal phase precipitation. (Cuo.36Zr0.48Al0.08Ag0.08)100-xFex (x=10,15,20) alloys system, thereare crystal phase Cu10Zr7 and FeZr3 presence, reducing the strength of the composite at the same time, and did not increase the material plasticity, we can see crystal phase Cu10Zr7 and FeZr3 great brittleness.