Neutron Activation Analysis of Ultrahigh-Purity Ti-Al Alloys in Comparison with Glow-Discharge Mass Spectrometry

Abstract

Neutron activation analysis (NAA) of ultrahigh-purity Ti–Al alloys has been performed without chemical treatments using normal and graphite-shielded irradiations. The Ti–Al alloys were made of ultrahigh-purity Ti (99.9999 mass% or 99.995 mass%) and Al (99.9998 mass%) by melting in ultrahigh vacuum with a copper-crucible induction-heating furnace. Concentrations and detection limits were evaluated for 35 impurity elements analyzed also by glow-discharge mass spectrometry. Seven impurity elements As, Cu, Ga, Na, Mn, Sb and W were detected by NAA. The sensitivities of NAA for Ga, In, Mn, Sb and Sc were better than those of glow-discharge mass spectrometry. Differences between the two analytical methods were mostly acceptable. The effectiveness of the graphite-shielded irradiation to suppress fast neutron reactions was clearly demonstrated.