This application note demonstrates the performance of the Axios FAST XRF spectrometer for the analysis of titanium alloys.
Accurate and fast elemental analysis during the production process of titanium and its base materials is a critical requirement. Measurements were performed using an Axios FAST simultaneous X-ray fluorescence spectrometer equipped with a 4 kW Rh SST-mAX X-ray tube.
Titanium is a relatively new metal and was first produced in 1906. Larger quantities (20 kg) were produced by William J. Kroll in Luxembourg between 1932 and 1938. The present production process carries his name. Titanium metal is characterized by a high melting point (1675 ºC), high strength and a low density (4.51 g/cm2). Despite the high price of titanium, its unique properties explain its increasing application in aviation and the space industry, where a high strength to weight ratio and high temperature resistance are often of prime importance. Further, its high resistance to corrosive products makes it ideal as a lining in tubing for the chemical industry. To change its properties it can be easily alloyed with other metals. Accurate and fast elemental analysis during the production process of titanium and its base materials is a critical requirement. The Axios FAST is ideally suited for many applications where speed and accuracy are factors of prime importance. This application note demonstrates the performance of the Axios FAST XRF spectrometer for the analysis of titanium alloys.
Measurements were performed using an Axios FAST simultaneous X-ray fluorescence spectrometer equipped with a 4 kW Rh SST-mAX X-ray tube, set at 60 kV/66 mA for optimal measurement conditions. A 300 μm brass tube filter and a brass beam-stop were mounted. Further it was equipped with:
Thirty-five proprietary titanium standards were used to set up calibrations. The samples were re- surfaced prior to their measurement. Due to their diameter, the samples were mounted in 27 mm aperture sample holders. Since the spectrometer was equipped with a 37 mm aperture reference plate the sample holders were gold-plated to avoid spectral contamination.
Axios FAST, our high-end simultaneous X-ray spectrometer, is the first choice for fast analytical control in demanding industries.
Combining the revolutionary 4 kW SST-mAX X-ray tube with Zeta technology, advanced counting electronics and well-proven features developed over several generations of industry-standard spectrometers, the Axios FAST ensures faster than ever sample processing, together with outstanding operational reliability.
Total adaptability to the automation of analysis was a key consideration in the design of Axios FAST. Facilities extend from the pre- programmed measurement of single samples to incorporation of the spectrometer into self monitoring shop-floor or containerized laboratories.
For a full simultaneous spectrometer, the analysis speed is usually determined by the element with the lowest sensitivity and/or the lowest concentration (Ru in this case). Despite the short counting times of 10 seconds or less, excellent results were obtained for all elements, including those measured for a few seconds with a programmable goniometer. Table 1 gives an overview of the elements with their concentration range, their respective values for the ‘root mean square’ (RMS) error, for K and for the lower limit of detection (LLD) based on a 100 second counting time. The values for RMS and K are absolute and relative indications respectively, of the magnitude of the differences between the measured concentration and the supplied chemical concentration.
A lower value for K indicates a more accurate calibration. Since the RMS value relates to the whole concentration range, a better estimate for the absolute error of a specific element with a known concentration can be obtained by using a formula based on the K value:
For example, error estimates for Al determinations of 1.0 and 10.0 wt% based on the calibration detailed in Table 1 (where K = 0.024) would be 0.024 wt% and 0.076 wt%, respectively.
V, Cr and Mn were measured with different channel configurations to illustrate the relative performance characteristics of the fixed channel and goniometer options. The values for V show that the measurements with the fixed channel (V) and the focusing goniometer (V1) are very comparable. The results of the compact goniometer (V2) are slightly worse.
For Cr the accuracy of the two calibration lines is very similar, however the LLD obtained with the focusing goniometer is better than with the fixed channel. For Mn the fixed channel and the compact goniometer channel give similar results, whereas the results obtained with the focusing goniometer are slightly worse.
Element | Concentration
range (wt%) | K
| RMS
(wt %) | LLD for t=100
(ppm) |
|---|---|---|---|---|
| Al
| 0.01 - 12.0
| 0.02
| 0.05
| 2.2 |
| Si
| 0.00 - 0.22
| 0.02
| 0.008 | 1.1 |
| *Ti1
| 80 - 100
| 0.03
| 0.3
| Not applicable
|
| V
| 0.0 - 5.1
| 0.02
| 0.03
| 11 |
| V1 | 0.0 - 5.1
| 0.02
| 0.03
| 13 |
| V2
| 0.0 - 5.1
| 0.04
| 0.04
| 33 |
| Cr | 0.0 - 4.2
| 0.02
| 0.02
| 26 |
| Cr1 | 0.0 - 4.2
| 0.02
| 0.03
| 14 |
| Mn
| 0.00 - 0.07
| 0.007
| 0.002
| 3.1 |
| Mn1
| 0.00 - 0.07
| 0.007
| 0.003
| 6.9 |
| Mn2
| 0.00 - 0.07
| 0.006
| 0.002
| 4.1 |
| Fe
| 0.0 - 2.2
| 0.014
| 0.007
| 3.4 |
| Co | 0.0 - 0.3
| 0.006
| 0.003
| 2.0 |
| Ni | 0.0 - 1.6
| 0.009
| 0.006
| 2.1 |
| Cu | 0.0 - 0.2
| 0.01
| 0.004 | 2.2 |
| Y2 | 0.000 - 0.011
| 0.002
| 0.0005
| 0.8 |
| Zr2 | 0.0 - 5.0
| 0.01
| 0.01
| 1.0 |
| Nb2 | 0.00 - 0.07
| 0.008
| 0.003 | 0.8 |
| *Mo | 0.0 - 4.0
| 0.011
| 0.02
| 1.3 |
| Ru2 | 0.00 - 0.07
| 0.006
| 0.002
| 4.0** |
| Pd2 | 0.00 - 0.15
| 0.02
| 0.007
| 4.8** |
| Sn | 0.0 - 4.8
| 0.009
| 0.009
| 1.9 |
| Hf2 | 0.00 - 0.03
| 0.002
| 0.0005
| 1.8 |
| Ta2 | 0.00 - 0.10 | 0.01
| 0.004
| 5.5 |
| W | 0.00 - 0.38
| 0.01
| 0.005
| 5.1 |
| Bi2 | 0.000 - 0.049
| 0.003
| 0.0008
| 3.4 |
The following notation is used to distinguish the different measurement conditions: V1=gonio1, V2=gonio2, etc. *=beam attenuator used, **= tube filter used .
The Axios FAST is perfectly suited for analyzing an extended range of concentrations for various types of titanium alloys within one analytical program. A high accuracy of analysis is achieved for both fixed channels and channels programmed on the two types of goniometer. A total of 54 seconds counting time was used to achieve results for 26 channels. Adding more fixed channels rather than using goniometer channels can reduce the total counting time to a minimum of 10 seconds. The use of larger samples and sample holders with larger diameters (e.g. 37 mm), will further decrease values for the LLD’s if required.
