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The article presents a list of papers published in the vol. 39 and 40 of the "Journal of Materials Science." Some of the papers are, "Adhesively-Bonded Joints and Repairs in Metallic Alloys, Polymers and Composite Materials," by A. Baldan, "Thermo-Mechanical Fatigue of Shape Memory Alloys," by E. Hornbogen, "Electrical Applications of Carbon Materials," by D.D.L. Chung, and others.

Consolidated nano/sub-micron AZ31 Mg alloy is a new structural material that combines nano-scale grains with a size of up to 100 nm and sub-micron grains with a size of up to 300 nm. Inherently, this new material should have significantly improved strength, making it a potential candidate for special applications requiring increased specific strength. The present paper evaluates the properties of nano/sub-micron AZ31 Mg alloy in terms of mechanical properties and corrosion resistance. The obtained properties are explained and associated with the micro-structure of the alloy. In addition, the nano/sub-micron structural alloy was compared to conventional extruded alloy with the same composition in order to distinguish the main differences between the two alloys. [ABSTRACT FROM AUTHOR]

The present paper describes a surface-microstructural modification due to cold work and the fatigue behaviour of the surface-modified specimens in beta Ti-22V-4A1 alloy. As-solution treated specimens were shot peened and then aged to achieve the modification. The obtained microstructure was first characterized and rotating bending fatigue tests were then performed using the surface-modified smooth specimens. The fatigue behaviour was evaluated and compared with the results of the conventional solution treated and aged specimens without modification. Surface-microstructural modification was successfully achieved within the region of 350 µm underneath the surface where hardness increased significantly compared with the core of the specimen, although there were some inhomogeneous precipitation areas in the modified region. The specimens without modification showed a step-wise S-N curve with the transition stress of approximately 600 MPa below which subsurface fracture occurred, while the surface- modified specimens did not exhibit step-wise S-N curve, but both surface-related and subsurface fractures took place up to a higher stress level of 720 MPa, leading to improved fatigue strength. In the surface-modified specimens, several facets were seen at the subsurface crack origin. The initiation sites were deeper than the specimens without modification, which corresponded to the in homogeneous precipitation areas. The subsurface fracture process is further discussed on the basis of some mechanical approaches. [ABSTRACT FROM AUTHOR]

Impact toughness as a property has been acquiring increased importance in recent years, since data regarding this property can provide a means for assessing alloy ductility under high rates of deformation. The main objective of this study is to investigate the effects of Sr-modification, Fe-based intermetallic phases and aging conditions on the impact toughness of widely used 356 alloys. The total absorbed energy was measured using a computer-aided instrumented Instron Charpy impact testing machine. Increasing the level of iron additions decreases the impact energy values of 356 alloys to a noticeable degree (~35-57%). The addition of 0.1 wt% Mn to non-modified 356 alloys seems to have no observable effect on the impact energy, while increasing the Mn addition to 0.4 wt% produces a slight improvement in the impact energy values for non-modified and Sr-modified 356 alloys compared to that of those containing only iron under the same conditions. The application of solution heat treatment in combination with Sr-modification was found to significantly improve the impact energy of as-cast 356 alloys, particularly at low iron additions. Artificial aging of non-modified and Sr-modified 356 alloys at 180 °C diminishes the impact energy values with an increase in the aging time up to 8 h compared to those obtained under the solution heat-treated conditions. On the other hand, aging at 220 °C for 12 h increases the impact energy values of Sr-modified 356 alloy containing 0.12 wt% Fe and combined 0.2 wt% Fe-0.1 wt% Mn to about 20 and 18 J, respectively. The fracture behavior of non-modified 356 alloys containing 0.12 wt% Fe is mainly controlled by the acicular eutectic Si particles whereas β-iron platelets act as crack initiation sites and provide further path for final crack propagation in non-modified 356 alloys containing 0.9 wt% Fe. The β-iron platelets and π-iron phase particles contribute largely to crack initiation and propagation in the Sr-modified 356 alloys containing 0.9 wt% Fe. [ABSTRACT FROM AUTHOR]

The strength and quality of an Al-Si alloy casting are determined by its microstructure and the amount of porosity present in the casting. Modification is one of the processes used to improve the microstructural quality, where the addition of a modifying agent alters the shape of the eutectic Si from an acicular to a fibrous form that is extremely beneficial to the mechanical properties. Among various modifiers, strontium has been used extensively, as it is easier to handle and more resistant to fading. However, its addition is also associated with porosity formation in these alloys. The porosity formed in Sr-modified castings has been variously related to an increase in the hydrogen level of the melt, feedability problems in the mushy zone during solidification, and changes in the mode of eutectic nucleation—from near the α-Al dendrites in the Sr-free alloy, to within the eutectic liquid itself in the Sr-containing alloy. The present study was carried out to determine the influence of oxides on the porosity characteristics observed in Al-Si alloys containing strontium. A series of experimental and industrial alloys viz., Al-7%Si, Al-12%Si, 319 and 356 were selected, to cover a variety of alloy freezing ranges. The techniques of thermal analysis, optical microscopy, and SEM/EDX and EPMA analyses were employed to obtain the results presented here. It is seen how the presence of oxides (Sr and Al) is responsible for the porosity formation observed in Al-Si alloys, and that the difference in porosity characteristics with the addition of Sr depends on the amount of Sr oxides present in the solidified structure. The presence of aluminum oxide films leads to the formation of large pores that are often linked together. Both aluminum and strontium oxides are favorable sites for the nucleation of other microconstituents. [ABSTRACT FROM AUTHOR]

Sn-Bi-Ag-(ln) solder alloys have been extensively studied in the study. The experimental results reveals that the liquidus temperatures of Sn-(1-5) Bi-(2-3.5)Ag-(0-10)ln solders are between 201.7 and 225.3°C, which were higher than that of the most popular eutectic Pb-Sn solder (183°C). Additions of (5-10) wt% In into Sn-Bi-Ag solders can effectively decrease the melting point of the solder alloy. However, the gap between Ts and TL temperatures increases with the additions of Bi and In into Sn-B i-Ag-(ln) solders. Although there is no flux applied during soldering, most Sn-Bi-Ag-(ln) solder alloys can well bond the Au/Ni metallized copper substrate. 945n-3Bi-3Ag solder demonstrates the lowest wetting angle of 45° among all test samples. Thermal expansion coefficients of both 945n-3Bi-3Ag and 90Sn-2Bi-3Ag-5In solders are slightly less than that of 63Sn-37Pb. Both 90Sn-2Bi-3Ag-5In/substrate and 945n-3Bi-3Ag/substrate interfaces demonstrate similar reaction kinetics in the experiment. The stability of the interface is greatly impaired during 90°C aging. Some locations of the electroless Ni layer break down, and new phases are formed nearby the interface during aging treatment. Initially, the growth of Ni-rich (Ni,Cu)3Sn4 phase dominates the interfacial reaction. However, the growth of Cu-rich (Cu,Ni)6Sn5 phase will dominate the reaction layer for specimens aged at 90°C for long time periods. [ABSTRACT FROM AUTHOR]

The Al-Cu-Mg-Si alloying system is a base for a diverse group of commercial alloys which acquire their properties after quenching and aging. Therefore, the knowledge of the phase composition of hardening precipitates and the conditions under which they are formed is very important. Vast reference data were analyzed along with experimental results and calculations of phase equilibria. Different alloys were compared based on the composition of the supersaturated solid solution. It is shown that the phase composition of aging products in alloys with Mg : Si>1 agrees well with the equilibrium phase composition at a temperature of annealing. However, the sequence of precipitation in the alloys with Mg : Si < 1 is more complicated. The hardening in these alloys occurs with precipitation of the β" and θ' phases and their precursors. The former phase may contain copper and later transforms either to β' and β (Mg2Si) or to Q phase depending on the amount of copper and annealing temperature. [ABSTRACT FROM AUTHOR]

In this work the results of the experimental study of surface tension (ST) of alkali metals and their Na-K-Cs ternary system over the whole composition range and for temperatures from the melting point to 680 K are presented. Careful thermal treatment for several hours at 700 K under 10- 7 Pa vacuum condition and a new way of loading the measuring cell have been used to exclude possible contamination of the liquid metals and the measuring cell. To measure ST the sessile-drop method, which yields an experimental error of 1% with 95% probability, was used. Contents of impurities were not larger than 0.005%.Surface tensions of 110 Na-Cs-K alloys have been measured over the whole composition triangles for the first time. Polytherms of ST for pure metals and ternary alloys are well described by linear equations. The isotherms of ST for each Na/Cs +Ksection have been constructed. It was found thatKis a surface-active addition in ternary alloys when XNa:XCs>14:1, while it becomes a surface-inactive component if XNa:XCs<14:1. All ternary alloys along the XNa:XCs = 14:1 section have the same ST, independent fromKcontent. Lines of equal values of ST have been plotted for the whole composition triangles as well. [ABSTRACT FROM AUTHOR]