ISO/TC 155/WG 10 - Nickel alloys analysis

This document specifies a spectrophotometric method for the determination of the phosphorus content in nickel, ferronickels and nickel alloys between 0,000 5 % (by mass) and 0,05 % (by mass). Arsenic, chromium, hafnium, niobium, silicon, tantalum, titanium and tungsten interfere, but the interferences can be avoided by complexation or volatilization (for chromium). The lowest phosphorus content [0,000 5 % (by mass)] can only be reached in samples with low contents of these interfering elements.

This document specifies a molecular absorption spectrophotometric method for the determination of titanium content in nickel alloys. The method is applicable to titanium contents between 0,3 % (mass fraction) and 5,0 % (mass fraction). Molybdenum, if present in the alloy, can cause a high bias in the reported titanium value to the extent of 0,001 % Ti for every 1,0 % Mo. NOTE 1 Evidence exists that extension of this method is possible for titanium contents down to 0,05 % (mass fraction). NOTE 2 Modifications in the general method allow the determination of titanium in alloys containing tungsten and/or tantalum.

This document specifies an inductively coupled plasma optical emission spectrometric method for the determination of tantalum contents between 0,1 % and 5 % in nickel alloys.

ISO 7529:2017 specifies a potentiometric titration method for the determination of chromium content in nickel alloys which do not contain insoluble carbides and which have a vanadium content less than a mass fraction of 0,2 %. The method is applicable to chromium contents between a mass fraction of 5 % and a mass fraction of 22 %. Vanadium, which can be present as an impurity in the alloy, will give a positive bias interference. However, at a level of a mass fraction of 0,2 %, this bias is equivalent to a mass fraction of 0,068 % chromium, which is about half the reproducibility of the method.

The principle of the method specified is dissolving a test portion in hydrochloric and nitric acids, removing hydrochloric acid and nitric acid by evaporation to fumes in the presence of sulfuric acid, forming the titanium diantipyrylmethane complex, measuring the absorbance of the test solution at a wavelength of 390 nm. The method may be used to determine titanium contents in the range of 0,3 % (m/m) to 5,0 % (m/m). Evidence exists that extension of this method is possible for titanium contents down to 0,05 % (m/m); modifications allow to determine titanium in alloys containing tungsten and/or tantalum.