Analysis of copper alloys with the ARL X900 XRF Spectrometer

Significance of the topic

Accurate chemical analysis of copper alloys is essential for controlling mechanical and physical properties (conductivity, hardness, corrosion resistance, wear) that determine product performance across engineering, marine, electrical and coinage applications. Fast, precise and trace-capable methods are required for incoming material control, production monitoring and R&D. Wavelength-dispersive X-ray fluorescence (WDXRF) implemented in modern spectrometers provides high throughput, low detection limits and excellent precision for multielement analysis in copper matrices.

Goals and overview of the study

This application note characterizes the analytical performance of the Thermo Scientific ARL X900 Simultaneous–Sequential WDXRF spectrometer for a wide range of copper alloys (brass, bronze, cupro‑nickel, nickel silver, etc.). The work evaluates limits of detection (LoD), short‑term precision (repeatability) across representative alloy matrices, and operational features such as the Moiré fringe goniometer and fixed‑channel monochromators under typical counting times and power settings.

Methodology

• Instrument operation: WDXRF measurements were made using fixed monochromator channels and selected goniometer channels. Typical test power levels were 3500 W and 4200 W.
• Counting times: Standard per‑element fixed channel counting time was 40 seconds (examples also report 100 s for LoD comparison). Goniometer channels were typically measured with 20 s per element while fixed channels measured concurrently.
• LoD determination: Limits of detection were calculated as 3× the standard deviation from repeated analyses (21 repeatability runs of a pure copper blank for LoD). For guaranteed specification, a factor of 1.5 is recommended.
• Precision testing: Short‑term repeatability tests comprised eleven consecutive runs on several representative matrices (low‑alloy copper, bronze, cupro‑nickel, brass) with the same sample preparation and measurement routines.
• Calibration: Calibrations can be provided using certified reference materials (CRMs) and delivered turnkey to reduce commissioning time. Identical sample preparation for CRMs and routine samples is stressed.

Used instrumentation

• Thermo Scientific ARL X900 Simultaneous–Sequential WDXRF spectrometer.
• Moiré fringe goniometer enabling sequential channel measurements while fixed channels are active; acts as backup for fixed channels.
• Fixed monochromator channels (up to 24 with goniometer fitted, up to 32 if no goniometer). New high‑counting fixed channel monochromators available for enhanced signal on major elements.
• Detectors: flow‑proportional (gas‑sealed) and scintillation (SCX) counters to cover light to heavy elements.
• Crystals and collimators: up to nine crystals and four collimators can be fitted for flexible channel configuration.
• Software: Thermo Scientific OXSAS control and data processing under Microsoft Windows.

Key results and discussion

Limits of detection and precision metrics demonstrate the ARL X900 is well suited for routine and R&D copper alloy analysis:

• Limits of detection in copper matrices (fixed channels): typical LoDs at 40 s per element were in the low ppm range for many elements (approximately 1–5 ppm for several light and mid‑Z elements) with some heavier or low‑yield lines showing higher LoD (up to ~10–12 ppm for particular lines). Extending counting time to 100 s produced noticeable LoD improvement (typical reduction ~30–50%).
• Short‑term repeatability: Eleven‑run tests on different matrices yielded very small standard deviations for major components: example Cu results were ~99.62% (low‑alloy copper) with std dev ≈0.0021, ~82.44% (bronze) with std dev ≈0.010, ~77.62% (cupro‑nickel) with std dev ≈0.007, and ~59.78% (brass) with std dev ≈0.012. Minor and trace elements also exhibited good precision when fitted as fixed channels.
• Goniometer vs fixed channels: Elements measured on the Moiré fringe goniometer are analysed sequentially while fixed channels run simultaneously; this allows extended elemental coverage without sacrificing throughput. However, elements with low fluorescence yield (As, Te, Bi, Ag and similar) show larger variability on goniometer channels and benefit from longer counting times or placement as fixed channels for best precision and LoD.
• High‑counting fixed channel monochromators and optimal detector selection (flow proportional vs scintillation) significantly improve precision and counting statistics for key alloying elements such as Cu, Zn and Ni.
• Practical LoD computation and reporting: LoD = 3σ derived from repeatability; background equivalent concentration (BEC) and counts per second per 1% element are the underlying metrics. The note recommends multiplying measured precision and LoD by 1.5 for guaranteed specifications.

Benefits and practical applications

• Comprehensive coverage: ARL X900 covers elements from boron to californium with appropriate detector/crystal choices, making it adaptable to diverse copper alloy chemistries (brass, bronze, aluminium bronzes, leaded bronzes, cupro‑nickels, nickel silver, etc.).
• High throughput: Simultaneous‑sequential design and Moiré goniometer maximize throughput by running many fixed channels while sequentially scanning others.
• Flexibility and robustness: Ability to fit multiple monochromators, detectors and collimators allows configuration to balance speed, LoD and precision. The goniometer also provides redundancy if fixed channels fail.
• Turnkey calibration and software: Factory or site calibrations using CRMs and OXSAS software reduce commissioning time and facilitate routine QC workflows.
• Application areas: Incoming material inspection, process control, final product QC, failure analysis and R&D alloy development.

Future trends and potential uses

• Detector and monochromator advances: Continued development of high‑count fixed channel monochromators and more sensitive detectors will lower LoDs and improve precision for both major and trace elements.
• Automation and data analytics: Integration with automated sample handling, advanced chemometrics and AI‑assisted calibration can enhance throughput, drift correction and matrix compensation in complex alloys.
• Method specialization: Dedicated methods (for example special treatments for Cu/Zn quantification or Bäkerud method referenced for improved Cu/Zn precision) and optimized goniometer configurations will tailor performance to specific industrial needs.
• Sample preparation standardization: Improved, reproducible sample preparation procedures remain critical to realizing instrument performance and ensuring accurate calibration transfer between CRMs and routine samples.

Conclusion

The ARL X900 WDXRF spectrometer provides fast, precise and flexible multi‑element analysis for a wide range of copper alloys. Demonstrated low ppm LoDs, strong short‑term repeatability across several alloy matrices, and adaptable channel/detector configurations make it suitable for routine QC, production monitoring and research applications. The Moiré fringe goniometer enhances elemental coverage without compromising throughput and serves as a practical backup to fixed channels. For low‑yield trace elements, allocating longer counting times or fixed channel fitting is recommended to meet detection and precision targets.

Reference

• Thermo Fisher Scientific. Application note AN41427: Analysis of copper alloys with the ARL X900 XRF Spectrometer. © 2025–2026 Thermo Fisher Scientific Inc.