anhydrous ammonia atmosphere. The characteristics of the precursor-derived product,the mechanical properties and microstructures of the composites were investigated by FT-IR, elemental analysis, XRD,flexural strength and SEM. The composites were amorphous, showing a high flexural strength of 114.5 MPa and a non-brittle failure behavior.
21.The crystallization behavior of fluorphlogopite,a glass-ceramic located in MgO-SiO2-Al2O3-K2O-F system was studied by varying the B2O3 content in the glass composition. DTA analysis revealed that the frist peak crystallization temperatures(Tc1)and glass transition temprature increased with increasing the particle size of each composition. DTA and XRD results indicated that the phlogopite crystallites probably transform monoclinic to trigonal(3t)polytype at a temperature in the range of 950-1000.
22.We report the deformation behavior of the Ni-based bulk metallic glass (BMG)by spark plasma sintering of amorphous powders,which have been prepared by a gas atomization. By spark plasma sintering of amorphous powders in the supercooled liquid region, a fully Ni-based BMG was successfully synthesized. Full densification was achieved by viscous flow of the amorphous powders in the supercooled liquid region during consolidation process. The strengh of about 2.4GPa was obtained in the consolidated BMG,which is comparable to that of the as-cast BMG(2.6GPa).
23.An increase in porosity content caused degradation in thermal-fatigue life and other mechanical properties. The fractographic examinations identified the pores and some intermetallics as the key microstructural features which promote damage and thermal-fatigue crack initiation sites in the specimens. Crack initiation and propagation is expected to occur sooner in regions of higher defects such as pores and large intermetallics. Progressive cyclic plastic deformation was also observed in constrained thermal-fatigue specimens.
测定结晶度的主要方法有哪些？简述影响结晶度得主要因素？
请谈谈你对时温等效原理的认识。