Effect Of Pressureless Sintering Process On The Mechanical And Thermal Properties Of ZnAl/Fe₄₈Cr₁₅Mo₁₄C₁₅B₆Y₂Amorphous Composites

In this dissertation, taking advantage of good superplastic characteristics of amorphous in supercooled liquid region, bulk Zn Al/Fe48 amorphous composites by adopting Fe48Cr15Mo14C15B6Y2 amorphous powder fabricated by gas atomization with toughness Zn Al alloy powder were prepared using pressureless sintering methods in atmospheric environment. The characterization of the composite materials structure was analyzed by using X-ray diffraction(XRD), the microstructure and compression fracture morphology of the specimen morphology were analyzed by scanning electron microscope(SEM), and the thermostability was analyzed by differential thermal analysis(DSC), thermal conductivity and thermal diffusion coefficient of the specimen were analyzed by laser indeed thermal conductivity tester, in order to study the thermal conductivity of the Zn Al/Fe48 amorphous composites.The results illustrate that density of the Zn Al/Fe48 amorphous composites increases with the increase of Zn Al alloy content and the sintering temperature, and the composite materials can get relatively compact at 640 ℃ sintering temperature. There is no other crystal diffraction peaks in addition to the Zn Al alloy diffraction peaks in the diffraction peak of the Zn Al/Fe48 amorphous composites, and the basement is still Fe48 amorphous diffuse scattering peak, which illustrate that the addition of Zn Al alloy has not affected to the essence of Fe-based amorphous matrix. The surface of the composite materials after sintering is a continuous plane, there is no other crystal phase except for Zn Al phase, and the interfacial ad hesion of Fe48 amorphous matrix with Zn Al phase interface is tight, there exists a dissolving diffusion at the interface, but the interface area is only about 2 ~ 3 micron interface diffusion layer, and there is no interface reaction phase in sintering pro cess.Through the analysis of the compression stress-strain curve on the Zn Al/Fe48 amorphous composites, Zn Al alloy improves the toughness of the Fe48 amorphous materials obviously. The yield strength of composite materials which were measured in experiment is lower than Reuss model predicted value, but basically keeps consistent. Combined with its compression fracture morphology, the fracture mechanism of the Zn Al/Fe48 amorphous composites is mixed fracture mechanism which coexist ductile fracture and brittle fracture, however, the macro performance is brittle fracture.Through the analysis of DSC curve of the Zn Al/Fe48 amorphous composites, the amorphous matrix nature slightly changes, and there is no other crystal phase except for Zn Al phase, which illustrate that Zn Al alloy impacts on the thermal stability of Fe48 amorphous matrix little, and the amorphous matrix still remain completely. Within the scope of the 298 K to 423 K, the heat conduct ion coefficient of the Zn Al/Fe48 amorphous composites with 45 vol.% contents of Zn Al alloy is lower than that of Fe48 amorphous materials, the Zn Al/Fe48 amorphous composites with 65 vol.% contents of Zn Al alloy has higher thermal conductivity than other samples. Different sintering temperature has little effects on the thermal conductivity of the Zn Al/Fe48 amorphous composites. The thermal conductivity and thermal diffusion coefficient of the amorphous composites increase with the rising of temperature, but slightly changes with raising the temperature, which show that the Zn Al/Fe48 amorphous composites prepared by pressureless sintering have good heat preservation performance.