Microstructure,mechanical response and fractography of AZ91E/Al_(2)O_(3)_(p) nano composite fabricated by semi solid stir casting method

The present study confers to the fabrication and its characterization of magnesium alloy(AZ91E)based nano composites with nano Al_(2)O_(3) particulate reinforcements.A novel Semi Solid stir casting technique was adopted for the fabrication of the composite.An average particle size of 50 nm was used as reinforcement to disperse in matrix.The effects of change in weight fraction of reinforcements on the distribution of particles,particle–matrix interfacial reactions,physical as well as mechanical properties were reported.The SEM and EDS analysis has shown the uniform distribution of particles in the composite along with the presence of elements.The mechanical properties of reinforced and unreinforced composite were evaluated and presented.Fractography of tensile specimens was also discussed.

Influence of Ni interlayer on interfacial microstructure and mechanical properties of Ti-6Al-4V/AZ91D bimetals fabricated by a solid–liquid compound casting process

The solid–liquid compound casting of Mg-AZ91D and Ti-TC4 alloys was developed by using pure Ni electro-deposited coating.The pouring temperatures of 660℃,690℃,720℃and 750℃were chosen to investigated the effects of casting temperatures on microstructural evolution,properties,and fracture behaviors of Ni-coated TC4/AZ91D bimetals by the solid–liquid compound casting(SLCC).The scanning electron microscopy(SEM)and the energy dispersive spectroscopy(EDS)results showed that the interfacial zone mainly composed of nickel,Mg_(2)Ni and Mg-Al-Ni in the bimetals cast at 660℃.As the pouring temperature was increased to 750℃,the width of the interface zone,which mainly composed ofδ(Mg),Mg_(2)Ni,Mg-Al-Ni,Mg_(3)TiNi_(2) and Al_(3)Ni,gradually increased.The microhardness tests showed that the micro-hardness of the interface zone was smaller than that of TC4 substrate but larger than that of the cast AZ91D matrix.At the pouring temperature of 720℃,the Ni-coated TC4/AZ91D bimetals had the most typical homogeneous interface,which had granular Mg-Al-Ni ternary phase but no ribbon-like Al3Ni binary phase,and achieved the highest shear strength of 97.35MPa.Meanwhile,further fracture behavior analysis showed that most fracture failure of Ni-coated TC4/AZ91D bimetals occurred at the Mg_(2)Ni+δ(Mg)eutectic structure and Al_(3)Ni hard intermetallic.

Cross-sectional structure, microstructure and mechanical property evolutions of brass cladding pure copper stranded wire composite during drawing

A solid/liquid continuous casting and composite technology was used to produce d8.5 mm brass cladding pure copper stranded wire composite billet and the composite billet was then drawn. The results showed that the composite billet had good surface quality, metallurgical bonding interface between brass and pure copper as well as elongation of 53.1%. Synergistic deformation degree between pure copper wire and brass cladding layer was high during drawing. With an increase of the total deformation amount, the plastic deformation of the pure copper wire reduced triangular arc gaps between the pure copper wires and the triangular arc gaps were fully filled at 50%. When the total deformation amount was increased to 63%, dislocation cells and microbands successively formed in the pure copper wire. In the brass cladding layer, planar dislocation networks, twins and shear bands formed successively, and the main deformation mechanisms were dislocation sliding, twinning and shear deformation. The tensile strength increased from 240 MPa of the composite billet to 519 MPa of the one with the deformation amount of 63%, but the elongation decreased from 53.1% to 3.2%. A process of solid/liquid continuous casting and composite forming→drawing can work as a new compact method to produce brass cladding pure copper stranded wire composite as railway through grounding wire.

Tracing the Historical Development of Ethnic Colleges and Universities to Strengthen the Consciousness of the Chinese National Community:Oral Narratives of Southwest Minzu University's 70 Years of Development

"With copper as a mirror,you can wear a crown;with history as a mirror,you can know the rise and fall."This paper takes the 70-year development process of Southwest Minzu University as the carrier,the casting of the Chinese national community as the main line while tracing back to the source,adopts the recording method of"oral history of the school,"interviews witnesses to the development of Southwest Minzu University,including school leaders,teachers,alumni,and other representative figures,records the memories of these parties on the practices of Southwest Minzu University in different periods to cast the awareness of the Chinese national community,and collates them into a text.From the perspective of students,it is important to understand the history of the Chinese national community in the past 70 years since the establishment of Southwest Minzu University,collect and sort out the historical memories of Southwest Minzu University for the education of the Chinese national community,supplement and confirm the school's historical documents,preserve the history,make up for the gap in the history of the school,and at the same time provide a realistic basis for Southwest Minzu University to formulate future development strategies.