No abstract

Thermogravimetric analysis (TGA) testing was used to measure the change in weight of polished samples of Al-XSi (X = 0 and 1.2 mass%) alloys. The samples were heated at 843 K for 6 h in dry air or nitrogen gas. X-ray diffraction was used to monitor the formation of the oxide films on the surface of the samples. The surface oxide films were more compact after the Al alloy samples were heated in air, and the oxide films showed some cracks after being heated in nitrogen gas. The thermally formed surface oxide films on the Al-1.2 mass% Si alloy samples heated in air and in nitrogen gas possessed loose structures, which comprised mainly c-alumina, diaspore, and gibbsite, along with metallic silicon and/ or aluminum. The weight variation curve of the films appeared serrated; this can be attributed to chain reactions (3Si + 3O 2 ? 3SiO 2 + 4Al ? 3Si + 2Al 2 O 3 ) that occurred within the film.

No abstract

The effects of Ar Plasma Treatment (APT) on the properties of Ta i.e. the transformation from high resistivity β-Ta to low resistivity α-Ta are manifested in this work. It is demonstrated that APT indeed promotes the formation of low resistivity α-Ta, as confirmed by the lower sheet resistance and more α-Ta in XRD patterns compared to the case without APT. XPS results reveal that the compositions of interfacial thin layer between Ta and TaN are different in two cases. The precession electron diffraction (PED) is used to determine the degree of crystalline in Ta. It is indicated directly that both α-Ta and β-Ta exist in the Ta layer. The Kelvin Resistor Chain (KRC) and Chain Contact Resistance (Chain RC) test results show that APT could also lead to remarkably reduced contact resistance.

No abstract