Experimental evaluation of melting point depression in AlSi/AlN nanomultilayer system

Joanna Lipecka 1Mariusz Andrzejczuk 1Malgorzata Lewandowska 1Jolanta Janczak-Rusch 1,2Gunther Richter 3Lars Jeurgens 2

1. Warsaw University of Technology, Faculty of Materials Science and Engineering, Woloska 141, Warsaw 02-507, Poland
2. Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Joining Technologies and Corrosion (EMPA), Überlandstrasse 129, Dübendorf 8600, Switzerland
3. Max Planck Institute for Intelligent Systems, Central Scientific Facility Thin Film Laboratory (MPI), Heisenbergstrasse 3, Stuttgart 70569, Germany

Abstract

The aim of the study was to evaluate the structural changes in AlSi/AlN nanomultilayers (NML) upon annealing for low temperature joining applications. It is known that due to relatively high thermal sensitivity of nanometals, standard methods of joining, e.g. furnace brazing or welding, are not suitable as they cause e.g. grain coarsening. To overcome the limitations of conventional brazing technologies based on a bulk eutectic alloy approach, proposed research strategy aims to employ the size-dependent melting behaviors of metals confined in a nanostructured multilayer geometry. The use of such a nanoarchitectured configuration can reduce the processing temperature, thus allowing benign joining of heat sensitive nanometals. Nevertheless, before the step for application the basic understanding of the melting point depression occurred in such systems, its significance and possible mechanisms need to be deeply investigated, which is the main goal of this study.

The system investigated was produced by magnetron sputtering and consisted of Al-Si(12%) braze filler metal layers (bulk Tm=577°C) with a thickness of 4 nm alternated by aluminium nitride diffusion barrier layers with a constant thickness of 3 nm. The bilayer of AlN/AlSi was repeated 10 times on the Si substrate and covered with the final AlN layer on the top. In order to investigate the melting behavior, the system was heat treated at various temperatures and observed with the use of Scanning Electron Microscope (SEM). Further, the cross section FIB-lamellae of the as-deposited and the heat treated state directly under the droplet were cut and examined using a Scanning Transmission Electron Microscope (STEM) and Transmission Electron Microscope (TEM).

The TEM observations of the as-deposited state showed that the AlSi/AlN system consists of policrystalline layers of AlN and AlSi, where the layers possess very fine structure with the grain sizes similar to the corresponding film thicknesses. The chemical analysis using EDX revealed a homogenous distribution of both Al and Si throughout the AlSi layers, which suggests that the structure is single phase. The annealing at 300°C did not cause any significant changes in the multilayer structure, while the annealing at 400°C brought about a visible phase separation within the Al-Si layers, where the supersaturated solid solution transformed into Al reach and Si reach regions.

The SEM observation of metal-containing features created on the top of the nanomultilayer revealed their first appearance at a temperature of 400°C. The droplets had irregular shape and were randomly distributed on the surface. The chemical analysis on the cross section of a droplet showed that it consisted of Si and Al indicating that the droplets formed as a result of liquid metal outflow from the nanomultilayer. The STEM observations of the central region under the droplet revealed that the NML was partially damaged and became thinner. Some of the AlN layers were deformed and created bumps due to the accumulation of the AlSi alloy under them, while others were broken and removed and their fragments were embedded in a solidified AlSi droplet above the system.

Presented results demonstrate that the melting point depression in AlSi/AlN NML system reached the value of 177°C. The mechanism responsible for melting at depressed temperature consisted of two stages. In the first stage, at a temperature of 400°C phase separation within the AlSi layers occured. This led to the creation of privileged sites at the interface between AlSi and AlN layers, where the liquid Al-Si alloy was cumulated. In the second stage, the upper AlN layers became bent and beyond their bending strength, AlN layers started to deform and break, which allowed liquid metal to freely outflow and create a two-phase flower-like structures on the NML surface.

Related papers
  1. Joining ultrafine grained aluminium by friction stir welding - processing, microstructure and mechanical properties
  2. The influence of CeO2 on electrochemical performance of LiMn2O4.
  3. Nanotechnologie w gospodarce województwa podlaskiego
  4. Structural and electrochemical studies on LiMn2O4 cathode material for LIBs coated with ceramic oxides
  5. (Cd, Mn)Te Crystals for X and Gamma Radiation Detectors - an Alternative Material to CdTe and (Cd,Zn)Te. 
  6. Industrial perspectives of nanometals
  7. SEM studies of the etched surface of (Cd,Mn)Te
  8. Welcome address
  9. Atomic force microscopy characterization of corneocytes
  10. TiO2 nanotubes based composite layers for biomedical applications
  11. Scale up of nanometals production
  12. Możliwości badawcze Laboratorium Skaningowej Mikroskopii Elektronowej na WIM PW
  13. Otwarcie konferencji
  14. How to join heat sensitive materials?
  15. Reduced activation ODS ferritic steel – recent development in high speed hot extrusion processing
  16. The influence of grain refinement on the corrosion mechanism of 7475 aluminium alloy
  17. Wear resistance of the nanostructured 316 LVM austenitic stainless steel processed by hydrostatic extrusion
  18. Recrystallization and Grain Growth in Nano-structured Austenitic Stainless Steel under Electric Current Heating
  19. Grain refinement in CuCrZr by SPD processing
  20. Tailoring mechanical properties of nano-structured Eurofer 97 steel for fusion applications
  21. Microscopic and surface analytical characterization of TiO2 nanotubes produced by anodic oxidation and thermal treatment 
  22. Ceramic-polymer composites for medical application
  23. Microstructural and mechanical characterization of zirconia based composite
  24. The influence of nanosilica on wear resistance of ceramic-polymer composites intended for dental fillings
  25. Tailoring mechanical properties by grain refinement and particle redistribution
  26. Nowe materiały metaliczne o strukturze nanometrycznej do zastosowań w nowoczesnych gałęziach gospodarki
  27. Recent Advances in Making Nanometals by Heavy Plastic Deformation
  28. Morphological and surface analytical characterization of chemically pretreated Ti surfaces intended for biomedical applications
  29. Microstructure and mechanical properties of 7475 aluminium alloy processed by SPD methods
  30. Investigation of aqueous surface processes and corrosion mechanisms of Al-(Cu)-Fe-Cr quasicrystaline approximant
  31. On some peculiarities of electrochemical oxidation of Ti and Ti6Al6V alloy
  32. Nanomaterials in dental applications
  33. Nanostructure formation in austenitic stainless steel
  34. Evaluation of crystal structure and polytypism of SiC in microwave sintered diamond-SiC composite by TEM and HR-TEM
  35. Stability of second phase particles during processing by hydrostatic extrusion
  36. The influence of nano - filler on microstructure homogeneity and selected properties of dental ceramic - polymer composites
  37. Structural stability of zirconia ceramic in water and acid solutions
  38. Morphology and chemical characterization of Ti surfaces modified for biomedical applications
  39. Evaluation of degradation degree of dental hybrid composite used as permanent fillings
  40. The Wetting Behaviour and Interface Structure of Unreinforced and Particle Reinforced Lead-Free Solders
  41. Optimization of particle reinforced lead-free solders
  42. Microstructural evaluation during particles addition to lead-free solders
  43. Evaluation of fibre-cement interfacial properties by SEM-based push-out tests
  44. Fractography as a tool to optimize joint design and the brazing process
  45. Development of nanoparticle reinforced brazing filler metals and solders: the aspects of downscaling from micro to nanoscale
  46. Description of the mechanical performance of Cu-SnAgCu-Cu joints
  47. Size and constraining effects in lead-free solder joints
  48. Comparison of three different active filler metals used for brazing ceramic-to-ceramic and ceramic-to-metal joints
  49. The influence of hydrostatic extrusion on mechanical properties and tribological characteristics of an austenitic stainless steel
  50. On the Relief of the Residual Stresses in Ceramic-Metal Joints by a Layered Braze Structure
  51. MECHANISM OF GRAIN REFINEMENT IN ALUMINIUM ALLOYS IN THE PROCESS OF HYDROSTATIC EXTRUSION
  52. Model for intermetallic phase and intermetallic compound solidification during diffusion soldering
  53. Transition from solidification to the first solid/solid transformation during diffusion soldering
  54. The Influence of hydrostatic extrusion on microstructure of 6082 aluminum alloy
  55. SEM investigations of tooth/ filling bonding
  56. Development of microstructure and mechanical properties in nickel deformed by hydrostatic extrusion
  57. Nanometals for medical applications
  58. The influence of twin bands density on microstructure of 316LVM austenitic stainless steel subjected to transverse rolling
  59. Microstructure evaluation in an Al-Li alloy processed by severe plastic deformation
  60. EFFECT OF INITIAL MICROSTRUCTURE ON MECHANICAL PROPERTIES OF THE Al-Cu-Mg-Mn ALLOY PROCESSED BY HYDROSTATIC EXTRUSION
  61. SHRINKAGE OF DENTAL POLYMERIC COMPOSITES
  62. Microstructure and mechanical properties of binary Al-Li alloys processed by ECAP
  63. Microstructure of the ceramic - polymer composites for dental applications
  64. Hydrostatic extrusion and nanostructure formation in an aluminium alloy

Presentation: Poster at Nano PL 2014, Symposium A, by Joanna Lipecka
See On-line Journal of Nano PL 2014

Submitted: 2014-09-11 14:40
Revised:   2014-09-11 16:31
Google
 
Web science24.com
© 1998-2018 pielaszek research, all rights reserved Powered by the Conference Engine