Effect of rare earth Ce on the microstructure, physical properties and thermal stability of a new lead-free solder

Abstract

In this paper, in order to develop a low silver content lead-free solder with good overall properties, a newly designed solder alloys of Sn-0.3Ag-0.7Cu-20Bi-xCe type, with addition of varying amounts of rare earth Ce (0.05 mass%, 0.1 mass% and 0.2 mass%) were studied. The melting temperature of Sn-0.3Ag- 0.7Cu can be decreased substantially through addition of 20 mass% Bi; while the segregation of Bi element in the microstructure of the as-cast alloys can be relieved by micro-alloying with trace amount of rare earth Ce. Besides, aging treatments (160°C held for 6 h) of these solder alloys imply that appropriate amount of Ce addition can not only depress the diffusion induced aggregation of Bi in the microstructure but promote the homogenization during annealing. Compared with Bi-free Sn-0.3Ag-0.7Cu solder, Sn-0.3Ag-0.7Cu- 20Bi exhibits better wettability. More excitingly, the wetting property of Sn-0.3Ag-0.7Cu-20Bi can be further improved by doping little amounts of Ce, especially 0.5 mass%, in which case the spreading area of the solder can be increased to the largest extent. On the whole, the present study reveals that Sn-0.3Ag-0.7Cu- 20Bi-xCe (x=0.05-0.1) is a promising lead-free solder candidate considering the microstructure, melting temperature and wetting properties

The effect of thermal cycling in superplastic diffusion bonding of 2205 duplex stainless steel

“…During the experimental process, since the specimens has the cold roll reduction of 85%, significant recrystallization could be observed after the bonding process whether in the conventional way or using thermal cycling, as shown in Fig.6, and equiaxed grains were formed. Differed from Ostwald ripening effect observed after aging treated for 6h [25], this process took about 5min before the grains grew larger [26]. And the fine equiaxed grains provided favorable conditions for the completion of the diffusion bonding.…”

Characterization of fracture toughness and toughening mechanisms in Laves phase Cr 2 Nb based alloys

“…As for the HT alloys, the grain refinement mechanism is quite complex, since two opposite aspects containing the refining and potentially coarsening influences would coexist [15]. To discuss the effects of heat treatment in this study, three possible processes are specially considered.…”

Microstructure and grain refining performance of Ce on A380 alloy

“…Ce has been found very helpful and favourable for many other alloys and applications like hypereutectic aluminium alloys and lead-free solders [11]. The solidification of hypoeutectic Al-Si alloys with Ce addition can be described by Al-corner of ternary system Al-Si-Ce (Fig.…”

“…2) [12], which unfortunately does not include Figure 2. Al-corner of ternary system Al-SiCe [11,12] other alloying elements and other multicomponent phases with Ce. It was reported that these Ce-phases may act as nucleation sites for (Al) or (Si) crystals in both hypo-and hypereutectic Al-Si alloys [12,14].…”