Wang Richu

Mechanical properties and microstructure of as-cast and extruded Mg-(Ce, Nd)-Zn-Zr alloys ®

Studies on the mechanical properties and microstructures of as-cast and extruded Mg-Ce-Zn-Zr and Mg-Nd-Zn-Zr alloys have been made before and after heat treatment. The results show that the mechanical properties of as-cast Mg-Ce and Mg-Nd alloys are as good as those of typical die cast AZ91 alloy and the heat resistant WE43 alloy. In Nd-containing alloys, the precipitated phase Mg12 Nd contributes significantly to age hardening. The mechanical properties of extruded alloys are improved obviously compared with those of as-cast alloys. The ultimate strength is 257.8 MPa for extruded Mg-Ce alloy and 265.6 MPa for extruded Mg-Nd alloy. Extrusion is a useful method to improve both the strengths and elongations of the two experimental alloys at both ambient and elevated temperatures. The grain refinement and precipitation strengthening are the main strengthening mechanisms in the alloys. Tensile fracture surfaces show a dimple pattern after extruding and therefore reflect an improved elongation.

Magnetocaloric Effect of Alloys Gd(Al1 - x Cox)2

Abstract The magnetocaloric effect in alloys Gd(Al 1 - x Co x ) 2 with x = 0, 0.05, and 0.10 were investigated using X-ray diffraction (XRD) and magnetization measurements. It was found that three alloys crystallized in a single phase with MgCu 2 -type structure. The lattice parameter and Curie temperature decreased with increasing Co content, whereas the magnetic-entropy change increased. With a magnetic-field change of 2 T, the maximum of the magnetic-entropy change reached 4.6 J · kg −1 · K −1 near Curie temperature at approximately 95 K in the alloy GdAl 1.8 Co 0.2 , which appeared to be an alternative candidate for active magnetic refrigerants working in the temperature range centered at 100 K.

煅烧工艺对氧化锌铝(AZO)粉体光学性能的影响

采用聚丙烯酰胺凝胶法制备高浓度Al掺杂ZnO(AZO)前驱体( x (Al)=5.5mol%、6.5mol%), 研究煅烧工艺对AZO粉体光学性能的影响. 结果表明: 随着煅烧温度升高, Al在ZnO中的固溶度降低。当煅烧温度为750℃时, 生成ZnAl 2 O 4 相。提高煅烧温度, 粉体的紫外吸收峰从366 nm红移至373 nm; 延长煅烧时间, 紫外吸收峰发生蓝移, 吸收强度明显增大。室温下AZO粉体光致发光(PL)光谱主要由354 nm的紫外发射峰、406 nm的近边紫外发射峰和430 nm的蓝光发射峰组成。采用聚丙烯酰胺凝胶法制备高浓度Al掺杂ZnO(AZO)前驱体( x (Al)=5.5mol%、6.5mol%), 研究煅烧工艺对AZO粉体光学性能的影响. 结果表明: 随着煅烧温度升高, Al在ZnO中的固溶度降低。当煅烧温度为750℃时, 生成ZnAl 2 O 4 相。提高煅烧温度, 粉体的紫外吸收峰从366 nm红移至373 nm; 延长煅烧时间, 紫外吸收峰发生蓝移, 吸收强度明显增大。室温下AZO粉体光致发光(PL)光谱主要由354 nm的紫外发射峰、406 nm的近边紫外发射峰和430 nm的蓝光发射峰组成。