Response of Thin Films and Substrate to Micro-Scale Laser Shock Peening

2006 ◽  
Vol 129 (3) ◽  
pp. 485-496 ◽  
Author(s):  
Youneng Wang ◽  
Hongqiang Chen ◽  
Jeffrey W. Kysar ◽  
Y. Lawrence Yao
Keyword(s):  
Thin Films ◽  
Single Crystal ◽  
Single Crystal Silicon ◽  
Laser Shock Peening ◽  
Experimental Result ◽  
Subgrain Structure ◽  
Laser Shock ◽  
Crystal Silicon ◽  
Micro Scale ◽  
Shock Peening

Micro-scale laser shock peening (μLSP) can potentially be applied to metallic structures in microdevices to improve fatigue and reliability performance. Copper thin films on a single-crystal silicon substrate are treated by using μLSP and characterized using techniques of X-ray microdiffraction and electron backscatter diffraction (EBSD). Strain field, dislocation density, and microstructure changes including crystallographic texture, grain size and subgrain structure are determined and analyzed. Further, shock peened single crystal silicon was experimentally characterized to better understand its effects on thin films response to μLSP. The experimental result is favorably compared with finite element method simulation based on single-crystal plasticity.

Microscale Laser Shock Peening of Thin Films, Part 2: High Spatial Resolution Material Characterization

2004 ◽  
Vol 126 (1) ◽  
pp. 18-24 ◽  
Author(s):  
Wenwu Zhang ◽  
Y. Lawrence Yao ◽  
I. C. Noyan
Keyword(s):  
Thin Films ◽  
Spatial Resolution ◽  
Strain Field ◽  
High Spatial Resolution ◽  
Laser Shock Peening ◽  
Laser Shock ◽  
Stress Strain ◽  
Crystal Silicon ◽  
X Ray ◽  
Shock Peening

Microscale Laser Shock Peening (LSP) is a technique that can be potentially applied to manipulate the residual stress distributions in metal film structures and thus improve the reliability of micro-devices. This paper reports high-spatial-resolution characterization of shock treated copper thin films on single-crystal silicon substrates, where scanning x-ray microtopography is used to map the relative variation of the stress/strain field with micron spatial resolution, and instrumented nanoindentation is applied to measure the distribution of hardness and deduce the sign of the stress/strain field. The measurement results are also compared with 3-D simulation results. The general trends in simulations agree with those from experimental measurements. Simulations and experiments show that there is a near linear correlation between strain energy density at the film-substrate interface and the X-ray diffraction intensity contrast.

Characterization of Plastic Deformation Induced by Microscale Laser Shock Peening

2004 ◽  
Vol 71 (5) ◽  
pp. 713-723 ◽  
Author(s):  
Hongqiang Chen ◽  
Jeffrey W. Kysar ◽  
Y. Lawrence Yao
Keyword(s):  
Plastic Deformation ◽  
Single Crystal ◽  
Crystal Lattice ◽  
Electron Backscatter Diffraction ◽  
Fem Analysis ◽  
Copper Sample ◽  
Laser Shock Peening ◽  
Lattice Rotation ◽  
Laser Shock ◽  
Shock Peening

Electron backscatter diffraction (EBSD) is used to investigate crystal lattice rotation caused by plastic deformation during high-strain rate laser shock peening in single crystal aluminum and copper sample on 110¯ and (001) surfaces. New experimental methodologies are employed which enable measurement of the in-plane lattice rotation under approximate plane-strain conditions. Crystal lattice rotation on and below the microscale laser shock peened sample surface was measured and compared with the simulation result obtained from FEM analysis, which account for single crystal plasticity. The lattice rotation measurements directly complement measurements of residual strain/stress with X-ray micro-diffraction using synchrotron light source and it also gives an indication of the extent of the plastic deformation induced by the microscale laser shock peening.

The Use of Energy Dispersive Diffractometry to Measure the Thickness of Metal and Glass Thin Films

1981 ◽  
Vol 25 ◽  
pp. 365-371
Author(s):  
Glen A. Stone
Keyword(s):  
Thin Films ◽  
Single Crystal ◽  
Single Crystal Silicon ◽  
Substrate Material ◽  
Silicon Wafers ◽  
Energy Dispersive ◽  
Crystal Silicon ◽  
X Ray ◽  
Phosphosilicate Glass ◽  
Film Substrate

This paper presents a new method to measure the thickness of very thin films on a substrate material using energy dispersive x-ray diffractometry. The method can be used for many film-substrate combinations. The specific application to be presented is the measurement of phosphosilicate glass films on single crystal silicon wafers.

Numerical Investigation of Opposing Dual Sided Micro Scale Laser Shock Peening

2006 ◽  
Author(s):  
Yajun Fan ◽  
Youneng Wang ◽  
Sinisa Vukelic ◽  
Y. Lawrence Yao
Keyword(s):  
Residual Stress ◽  
Shock Waves ◽  
Laser Shock Peening ◽  
Time Lags ◽  
Laser Shock ◽  
Surface Residual Stress ◽  
Strain Rate Effects ◽  
Micro Scale ◽  
Stress Profiles ◽  
Shock Peening

Laser shock peening (LSP) is an innovative process which imparts compressive residual stresses in the processed surface of metallic parts to significantly improve fatigue life and fatigue strength of this part. In opposing dual sided LSP, the workpiece can be simultaneously irradiated or irradiated with different time lags to create different surface residual stress patterns by virtue of the interaction between the opposing shock waves. In this work, a finite element model, in which the hydrodynamic behavior of the material and the deviatoric behavior including work hardening and strain rate effects were considered was applied to predict residual stress distributions in the processed surface induced under various conditions of the opposing dual sided micro scale laser shock peening. Thus the shock waves from each surface will interact in different ways through the thickness resulting in more complex residual stress profiles. Additionally, when treating a thin section, opposing dual sided peening is expected to avoid harmful effects such as spalling and fracture because the pressures on the opposite surfaces of the target balance one another and prohibit excessive deformation of the target. In order to better understand the wave-wave interactions under different conditions, the residual stress profiles corresponding to various workpiece thicknesses and various irradiation times were evaluated.

Sign in / Sign up

Export Citation Format

Share Document