Cavitation and Bubble Dynamics: Preface

Wear resistance investigation of titanium nitride-based coatings

During the last decade the dc and rf sputtering techniques have been used extensively in their two configurations — balanced and unbalanced magnetron. The main applications have been in the fields of industry and research. Examples of industrial applications are: decorative thin films (Raymond & Baham, 1999), hard wear-resistant thin films (Rodil & Olaya, 2006), low-friction thin films (Heimberg et al., 2001) corrosion-resistant thin films (Flores et al., 2006), and thin films used as a protective optical system (Stefan et al., 2008), as well as maybe the most interesting applications, thin films used in the electronic industry (Monroy et al., 2011). In the research field, the investigation has been oriented toward understanding the main physical mechanisms, such as: interaction between charged particles and the surface of the target material, adherence between the substrate and the deposited material, and chemical reactions near the substrate, as well as the influence of the deposit parameters (substrate temperature, working pressure, density power applied to the target). This research has produced thin films with a high degree of crystallinity and with the possibility of various industrial applications.

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Thin Film Growth Through Sputtering Technique and Its Applications

Al3Ti reinforced Aluminium composites with different weight percent of Al3Ti particles were developed by in-situ reaction of aluminium alloy with potassium hexafluorotitanate (K2TiF6). Ultrasonication of the aluminium melt during salt reaction was carried out to refine the cast microstructure and achieve better dispersion of in-situ formed Al3Ti particles. The in-situ composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The Al3Ti particles generated in the melt promoted heterogeneous nucleation, which was responsible for grain refinement of the cast microstructure. The well dispersed Al3Ti significantly improved the mechanical properties including ductility, yield strength (YS), ultimate tensile strength (UTS) and hardness. The dominant strengthening mechanism in the composite was the thermal mismatch strengthening followed by Hall-Petch strengthening.

Strengthening mechanisms in ultrasonically processed aluminium matrix composite with in-situ Al3Ti by salt addition

Dissimilar friction stir welding of 6061 aluminum alloy and AZ31 magnesium alloy assisted with ultrasonic

Ultrasound assisted salts–metal reaction for synthesizing TiB2 particles at low temperature

Numerical modelling and experimental approach for surface morphology evaluation during ultrasonic shot peening

Ultrasonic shot peening (USP) is acknowledged as an effective surface treatment method to enhance the mechanical performance of materials by inducing compressive residual stress in solid metals and...

Overview of ultrasonic shot peening

As a promising reinforcement of aluminum alloy, in situ formed Al3Ti particles have attracted more attention in the fabrication of aluminum matrix composites. In our research, in situ Al3Ti/7075 alloy composites were fabricated by adding K2TiF6 salt powders into molten 7075 alloy at 750 °C via casting method. The formation of in situ Al3Ti particles and their effects on the microstructure and mechanical properties of 7075 alloy, including hardness, ultimate tensile strength (UTS), and yield strength (YS), were investigated. The results showed that in situ formed Al3Ti particles were rod-like in morphology, with the average length and width of 15 µm and 5 µm, respectively. Due to the nucleating effect of Al3Ti particles, α-Al crystals of 7075 alloy transferred from dendritic to equiaxed structure in morphology, the size of which decreased obviously as well. Compared with 7075 alloy, the hardness, UTS, and YS of in situ Al3Ti/7075 alloy were improved by 14.3%, 18.1%, and 25.8%, respectively.

In situ formed Al3Ti particles in Al alloy matrix and their effects on the microstructure and mechanical properties of 7075 alloy

This paper gives a brief overview of published results pertinent to ultrasonic shot peening, a relatively new method to introduce severe plastic deformations in the surface of materials and obtain nanosized grains. Among reported benefits are increased surface hardness and fatigue resistance, and possibility to perform nitriding at lower temperatures and in shorter times. Being a new technology, there is a lack in available literature on ultrasonic shot peening. For that reason, some of the results published for conventional shot peening are also presented. We believe, however, that the results selected here are transferrable to ultrasonic shot peening, or at least can serve as a reference point for this process.

Milan Rakita

Papers

Ultrasound assisted salts–metal reaction for synthesizing TiB2 particles at low temperature

Numerical modelling and experimental approach for surface morphology evaluation during ultrasonic shot peening

Overview of ultrasonic shot peening

In situ formed Al3Ti particles in Al alloy matrix and their effects on the microstructure and mechanical properties of 7075 alloy

Ultrasonic shot peening