Yutaka S. Sato

TL;DR: In this article, a novel technique of vacuum assisted via filling with molten solder was developed in which the diameter of the TSV was 30mm and its depth was 100-200mm.

Abstract: Weld nugget / stir zone microstructures often exhibit highly homogeneous distributions of non-deforming constituent phases as well as retinement of such phases and grain structures. The role of recrystallization in grain retinement during FSW/P is well understood. However, the processes involved in refmement of particle size and homogenization of particle distributions during FSW /P are less well understood. FS of an as-cast AA356 alloy has been conducted over a wide range of RPM values using both threaded and smooth tools. The conversion of the primary eutectic microstructure to a highly refined and homogeneous dispersion of Si particles in a finegrained Al matrix will be documented. The roles of advective mixing, diffusional processes, and discontinuous shearing of material will be delineated and quantitative measures of homogeneity will be discussed. The potential roles of tool and process conditions in homogenization are also considered. Homogenization via Advective Transport FSP is highly effective for intermixing of constituents in many alloys [1]-[3]. Given that observation, mass transport, either advective or diffusive, must occur to account for the observed constituent redistribution [4]. Here, model eutectic systems, AI-7%Si (Na moditied) and AA356 are considered, negating the need to account for the effects of phase transformations in the FSP temperature range. Experimental and analytical approaches showed that deformation-assisted, high-temperature diffusive processes do not appear to be sufficient, either in magnitude or duration, to account for the particle motion required to achieve the observed levels of redistribution [5]. Calculations can be carried out for temperatures approaching the melting point of the Al matrix to show that the induced hydrostatic pressure gradients would transport particles at particle drift velocities (-1 to 0.1 diameters/sec) that are insufficient to account for observed particle redistribution [5], [6]. Since FSP constituent mixing occurs in the very short time of a single tool rotation, i.e. less than 0.1 seconds, it is reasonable to conclude that an advective component oftransport must be significant. Here, the term 'advective' refers to the transport of entrained material resulting from the velocity of a surrounding viscous-like tlow field. Tn the case of a particle embedded in a highly plastic solid near its melting temperature, such behavior can occur. The advection equation in one dimension is given in Equation 1.

TL;DR: In this article, the microstructure distribution associated with hardness in the friction-bit-joined DP980 steel and the microstructural evolution during FBJ are reported, and then the micro-structures in the joint precisely.

TL;DR: In this paper, the microstructural evolution during friction stir welding of Ti-15V-3Cr-3Al-3Sn metastable-β titanium alloy was studied and the textural pattern formed in the stir zone was shown to be a mixture of 1 1 1 and 1 1 0 simple fiber textures.

TL;DR: In this paper, a twin-induced GBE utilizing optimized thermomechanical processing with small pre-strain and subsequent annealing was applied to introduce very high frequencies of CSL boundaries into a titanium-stabilized 321 austenitic stainless steel, which showed much higher resistance to intergranular corrosion after sensitization subsequent to carbon re-dissolution heat treatment during the ferric sulfate-sulfuric acid test.