ISO 14595:2014 pdf free

ISO 14595:2014 pdf free.Microbeam analysis – Electron probe microanalysis
Before heterogeneity testing is begun, the edges of bulk specimens should be analysed and compared to the specimen interior to determine whether there might be a consistent difference in element concentrations in the two locations. Occasionally, differences can result from the manufacturing process of materials such as metal alloys or synthetic crystals. If the edges are different from the specimen interior, they should be removed before samples are taken for bulk quantitative analysis and before specimens are mounted and polished for heterogeneity studies. In some specimens, differences might also be due to mounting and polishing procedures; if this occurs and cannot be remedied, the certificate should include instructions to the analyst to avoid using the material within a specified minimum distance from the edge.
Specimens that are being compared should be mounted together in the same sample mount or block, if possible. Carbon coating, if necessary, should be applied to all specimens simultaneously.
Tests should be designed to efficiently acquire the data needed to determine the extent of the within-specimen and between-specimen heterogeneity, to determine the experimental uncertainty, and to look for gradual increasing or decreasing concentration changes on the micrometre scale using 50 um to 100 um line scans. Examples of tests are given below, but they may be modified depending upon the individual material or group of specimens being analysed. The beam current should be monitored to provide a value corresponding to each data reading enabling subsequent current drift corrections to be carried out, if necessary.
NOTE It is advisable to collect data in an ASCII format that can be easily put into a spreadsheet for subsequent processing.
For each specimen being tested, X-ray counts for several, randomly selected points (typically7 to 10 or more depending upon the size of the specimen) should be acquired. These data should be acquired at least in duplicate i.e. integral X-ray counts should be acquired and recorded at least twice on each point without moving the specimen or electron beam between acquisitions. Specimens should be analysed in a random order and preferably, each specimen should be analysed twice, each time in a different order. It may be worthwhile for different operators to take data for duplicate analyses, using a different random sampling plan for each. Refer to ISO Guide 356] for sampling procedures and methods of evaluating results. The data from this type of test is used to calculate the within-specimen and between-specimen uncertainties, as well as the test uncertainty after beam current drift corrections are made. When background data are obtained for each element, the uncertainties can be expressed as a mass fraction.The formulae used for these calculations are given in 5.5.ISO 14595 pdf download.