Advanced Plasma Nitriding for Aluminum and Aluminum Alloys
Low hardness and wear resistance of aluminum alloys limit their use in practical application to automotive parts. Formation of hard aluminum nitride (AlN) layer on the surface can prolong the life time of aluminum automotive parts. Plasma nitriding was selected in the present study to form AlN layer on aluminum alloys. This processing is an environmental friendly method because of its low gas and energy consumption. Normal plasma nitriding requires long processing time to successfully form AlN layer. For advancing this surface treatment, refining microstructure and micro-alloying processes are proposed to activate the formation of AlN by plasma nitriding. Bulk Mechanical Alloying is used not only to make grain-size refinement but also to carry out micro alloying with addition of 1 mass%Ti. The formation rate of AlN layer is improved from 4:2 � 10 � 5 mm/s to 20:8 � 10 � 5 mm/s by microstructure refining. In particular, since the co-formed TiN with AlN works as a template in the initial state nitriding, the micro-alloyed aluminum can be nitrided even without pre-sputtering.
Diffusion studies using ion beam analysis
Abstract The combination of ion implantation with nuclear methods such as Rutherford Backscattering Spectrometry (RBS), Nuclear Reaction Spectroscopy (NRS) or Elastic Recoil Detection Analysis (ERDA) has shown to be well adapted to the study of impurity migration in solids induced by either thermal annealing or irradiation. This paper gives some typical examples studied in more detail in our laboratory. Among them, the determination of thermodynamical data (diffusion coefficients, activation energies) from the analysis of the evolution of implanted species is rather classical. As an illustration the diffusion study of lanthanum implanted into apatite using RBS is presented. This work is of interest with regard to nuclear waste storage in geological sites where apatites are possible migration barriers to radioactivity and lanthanum is a representative fission product. The second study taken from the metallurgical field concerns the determination of the nitrogen diffusion coefficient into aluminium using NRS. Finally, a study concerning hydrogen diffusion in an a-SiC:H material (plasma facing materials) induced by deuterium bombardment will be presented. The hydrogen profiling is performed using ERDA.
Ion beam analysis of nitrogen
Nitrogen plays an important role in almost all materials. In metals its presence influences the tribology. In semiconductors nitrogen compounds act as insulating. The less abundant isotope 15N can be used as tracer element to investigate biological processes. Thus the analysis of materials concerning the nitrogen content needs adequate methods. Nuclear reactions on both isotopes reveal an appropriate tool, if the cross sections are known to a high degree of accuracy.