It is well known that current fossil fuel usage is unsustainable and associated with greenhouse gas production. The amount of the world's primary energy supply provided by renewable energy technologies is urgently required. Therefore, the relevant technologies such as hydrogen fuel, solar cell, biotechnology based on nanotechnology, and the relevant patents for exploiting the future energy for the friendly environment are reviewed. At the same time, it is pointed out that the significantly feasible world's eco-energy for the foreseeable future should not only be realized, but also methods for using the current energy and their by-products more efficiently should be found correspondingly, alongside technologies that will ensure minimal environmental impact.

A review is provided about the current research on magnesium/magnesium alloys corrosion in the industry. Except for reviewing the kinds of corrosion on galvanic corrosion, stress corrosion, and corrosion fatigue, its corresponding mechanisms are also explained, such as the influence of metallurgical factors, and environmental factors. Furthermore, the protection of magnesium/magnesium alloys corrosion is presented, for instance, surface treatment/modification, coating and so on. Also, because the continuing challenges associated with the use of magnesium alloys, more considerations about future applications and research directions are given according to the properties improvement of magnesium alloys for the eco-friendly requirements.

Pulse Nd:YAG laser was used to polish DF2 cold work steel. Influence of irradiation parameters on the three-dimensional (3D) surface topography was studied by a 3D profilometer, scanning electron microscope (SEM) and atomic force microscope (AFM). Results among the tests showed that when DF2 steel specimens were irradiated with parameters of (i) laser input energy P51 J, (ii) pulse feedrate5300 mm min 21 , (iii) pulse duration PD53 ms and (iv) pulse frequency f520-25 Hz, the laser polishing of DF2 cold work steel seemed to be successful. The effect of laser polishing parameters on the laser polishing temperature was described and the analysis of the temperature field of laser polishing was herewith proposed initially. It demonstrated that for a given laser, the influence of the laser pulse feedrate was more prominent than that of other parameters on the topography of a laser polished surface. At a constant pulse duration and pulse frequency, the polishing temperature was increased with the increase in laser input energy and the decrease in the pulse feedrate.

The effect of in situ reaction on the microstructure of Nd:YAG laser welded joints of aluminum matrix composite SiC p /AlSi7Mg was studied. Results showed that the laser welding with Ti filler improved the tensile strength of welded joints. Moreover, the laser welding with in situ reaction effectively restrained the pernicious Al 4 C 3 forming reaction in the interface between aluminum matrix and reinforcement particles. Simultaneously, the reaction-formed TiC phase distributed uniformly in the weld. This permitted SiC p / AlSi7Mg composite to be successfully welded by Nd:YAG laser.

A review is given about the current state-of-the-art surrounding micro/nano scale welding/joining used in miniaturization or microsystems. Except for reviewing the applications of micro/nano welding/joining in various fields, such as microelectromechanical system (MEMS), micro total-analysis systems (microTAS), carbon nanotubes (CNTs) etc., the optimal equipments for micro/nano welding/joining, its corresponding future applications and research directions are discussed. Moreover, an extensive part of the paper is devoted to the introduction of new techniques, micro/nano laser and electron beam welding/joining. In turn, it is anticipated these techniques will be used in future micro/nano welding/joining applications. Meanwhile, because even smallest particles of dust can influence the results, more considerations are given to machine improvements that are required for its corresponding nano welding/joining. It will be one challenge for R&D efforts to combine the progress in micro/nano scales with that in miniaturization. This review provides a timely explanation of the literature surrounding the factors required for successful micro and nano welding/joining.