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The kinetics of diffusion processes on interlayer boundaries of the three-layered composites aluminum (AD1) + nickel (NP1) + aluminum (AD1) obtained by explosion welding with subsequent cold rolling is investigated. The phase comp...
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The kinetics of diffusion processes on interlayer boundaries of the three-layered composites aluminum (AD1) + nickel (NP1) + aluminum (AD1) obtained by explosion welding with subsequent cold rolling is investigated. The phase composition of the diffusion region is established.
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Cold wires of different chemistry (denoted as Types A and B) are ballbonded on identical metallization and isothermally aged at 175°C. In both wire types the same intermetallic compounds Au_4Al and Au_8Al_3 grow with parabolic ti...
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Cold wires of different chemistry (denoted as Types A and B) are ballbonded on identical metallization and isothermally aged at 175°C. In both wire types the same intermetallic compounds Au_4Al and Au_8Al_3 grow with parabolic time dependence as long as there is a supply of Al from the bondpad. After Al is completely reacted, composition of intermetallics in Type A wire remains unchanged but in Type B wire, the Au_8Al_3 compound undergoes a phase transformation into a second layer of Au_4Al. The phase transformation does not affect mechanical reliability of the ballbonds. Intermetallic growth kinetics, growth sequence and the possible origins of the phase transformation are discussed.
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The series of polycrystalline Y_xGd_(1-x)Fe_3 compounds with a PuNi_3-type of crystal structure have been obtained. Based on wide-ranging SQUID magnetometer series of different magnetic measurements have been carried out. Moreover...
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The series of polycrystalline Y_xGd_(1-x)Fe_3 compounds with a PuNi_3-type of crystal structure have been obtained. Based on wide-ranging SQUID magnetometer series of different magnetic measurements have been carried out. Moreover, the magnetic properties in the paramagnetic range has been studied by means of Faraday type magnetic balance. The partial replacement of Gd by Y atoms is reflected in the increase within the total saturation magnetic moment M_S from 1.61 μ_B/f.u (x=0.0) to 5.32 μ_B/f.u (x= 1.0) and the decrease of the Curie temperature T_C from 721 K (x=0.0) to 533 K (x=1.0). Exchange coupling parameters of R-R (A_(RR)), T-T (A_(TT)) and R-T (A_(RT)) have been evaluated from M(T) magnetization curves based on the mean field theory (MFT) calculation. The valence band spectra as well as the core level lines obtained by the use of X-ray photoemission spectroscopy (XPS) at room temperature have been analyzed as the influence of Gd/Y substitution on the electronic structure. The valence bands near the Fermi level are dominated by Fe3d states. A quite good agreement between the values of the iron magnetic moment estimated from M(H) curves, from MFT calculations as well as from fitting of Fe3s core level lines has been obtained.
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The equiatomic intermetallic compounds AETMg and AETCd (AE = Ca, Sr; T = Pd, Ag, Pt, Au) and the whole solid solution Yb_(2-x)PtMgx were synthesized from the elements in sealed niobium tubes in a high-frequency or a muffle furnace...
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The equiatomic intermetallic compounds AETMg and AETCd (AE = Ca, Sr; T = Pd, Ag, Pt, Au) and the whole solid solution Yb_(2-x)PtMgx were synthesized from the elements in sealed niobium tubes in a high-frequency or a muffle furnace. All samples were characterized on the basis of their powder X-ray diffraction patterns. The structures of SrAuCd, CaPdCd, CaPtCd, CaPdMg, SrPtMg, CaAg_(1.017)Mg_(0.983), SrAg_(1.032)Mg_(0.968), and Yb_(1.792)PtMg_(0.208) were refined on the basis of single-crystal X-ray diffractometer data. Some of the crystals showed small homogeneity ranges. All compounds crystallize with the orthorhombic TiNiSi type structure, space group Pnma. The crystal chemistry is briefly discussed and variations in chemical bonding as a result of the electronegativity of the transition metal are described.
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The title compounds were synthesized by arc-melting the elements in an argon atmosphere and subsequent annealing. #beta#-CeIr_2Si_2 and CeIr_2Ge_2 crystallize directly from the melt, while #alpha#-CeIr_2Si_2 was obtained after ann...
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The title compounds were synthesized by arc-melting the elements in an argon atmosphere and subsequent annealing. #beta#-CeIr_2Si_2 and CeIr_2Ge_2 crystallize directly from the melt, while #alpha#-CeIr_2Si_2 was obtained after annealing at 870 K. The three iridium compounds were investigated by X-ray diffraction on both powders and single crystals: ThCr_2Si_2 type, I4/mmm, a=408.82(2), c= 1016.96(6) pm, wR2=0.0546, 95 F_o~2 values, 9 variables for #alpha#-CeIr_2Si_2; CaBe_2Ge_2 type, P4/nmm, a=414.60(5), c=985.5(2) pm, wR2=0.0530, 361 F_o~2 values, 15 variables for #beta#-CeIr_2Si_2 and a=423.95(6), c=1010.1(2) pm, wR2=0.0750, 331 F_o~2 values, 16 variables for CeIr_2Ge_2. Refinement of the occupancy parameters indicated small defects on the Ir_2 site of CeIr_2Ge_2 resulting in the composition CeIr_(1.968(5)_Ge_2 for the investigated crystal. Striking structural motifs in these silicides and germanides are condensed distorted IrSi_(4/4) and IrGe_(4/4) tetrahedra and additionally IrSi_(5/5) and IrGe_(5/5) square pyramids in #beta#-CeIr_2Si_2 and CeIr_2Ge_2 forming three-dimensional infinite (Ir_2Si_2) and (Ir_2Ge_2) networks in which the cerium atoms fill cages of coordination number 18. The crystal chemistry and chemical bonding of these intermetallics are briefly discussed.
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The crystal structures of the TbZnSn_2 and TbZnSn compounds were determined by X-ray single crystal diffraction. The TbZnSn_2 compound crystallizes with the HfCuSi_2 structure type (space group P4/nmm) and TbZnSn crystallizes with...
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The crystal structures of the TbZnSn_2 and TbZnSn compounds were determined by X-ray single crystal diffraction. The TbZnSn_2 compound crystallizes with the HfCuSi_2 structure type (space group P4/nmm) and TbZnSn crystallizes with the YPtAs structure type (space group P6_3/mmc).
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Neutron powder diffraction experiments and magnetic measurements were performed on compounds of the series RFe9.5Mo2.5 (R = Y, Dy, Ho and Er). The influence of the R element on both the structural and the magnetic properties of th...
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Neutron powder diffraction experiments and magnetic measurements were performed on compounds of the series RFe9.5Mo2.5 (R = Y, Dy, Ho and Er). The influence of the R element on both the structural and the magnetic properties of the different compounds is discussed, as well as the possible correlation between the iron environments and the local moments. Comparison is made with a previous Mossbauer study on the same compounds. [References: 20]
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The Sn-3.2Ag-0.5Cu solder balls were joined with Sn-8Zn-3Bi paste on Cu Ni Au metallized BGA substrates at 240 deg C. The shear behavior of thus produced BGA package was investigated after multiple reflow and thermal aging. The tw...
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The Sn-3.2Ag-0.5Cu solder balls were joined with Sn-8Zn-3Bi paste on Cu Ni Au metallized BGA substrates at 240 deg C. The shear behavior of thus produced BGA package was investigated after multiple reflow and thermal aging. The two solders have mixed together and have no visible interfacial boundary. Moreover the void and the indent can be clarified occasionally close to the interface after reflow. The shear strength falls from 18.0 +- 1.6 N (one cycle reflow) to 14.8 +- 1.5 N (five cycle reflow) and remains roughly unchanged after 5 cycles up to 10 cycles (14.9 +- 2.1 N). Four types of fractures are observed in single cycle cases. The solder in which the voids exist may be sheared to descend the joint strength. The thickness of Ni-Sn-Cu-Zn compounds appears to be irrelevant to the shear behavior from 5 to 10 cycles. The shear strength drops from single to five cycles may be due to the spallation of excessive brittle Ni-Sn-Cu-Zn compounds into the solder which degrades the joint strength. The shear strength of the Sn-Ag-Cu Sn-Zn-Bi package changes little after aging at 150 deg C. The strengths are 17.5 +- 2.9, 16.9 +- 2.7, 17.6 +- 2.6 and 16.8 +- 2.4 N after aging for 100, 200, 500 and 1000h, respectively. As aging time increases, fractures shift to occur in the solder.
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The phase equilibria, A2/B2 and B2/L2_1 (or D0_3) order-disorder transitions and martensitic transformation on the Ni-Fe side of the Ni-Fe-Ga system were examined by electron probe microanalysis (EPMA) and differential scanning ca...
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The phase equilibria, A2/B2 and B2/L2_1 (or D0_3) order-disorder transitions and martensitic transformation on the Ni-Fe side of the Ni-Fe-Ga system were examined by electron probe microanalysis (EPMA) and differential scanning calorimetric (DSC) measurement. The equilibrium compositions of interrelations mainly among the alpha (A2), beta (B2), beta' (L2_1 or DO3), gamma (Al) and gamma' (Ll_2) phases were determined using diffusion triples which were fabricated by two-step diffusion coupling. It was confirmed that abcc single-phase region composed of a, beta and beta' at 850-1000 deg C exists in a wide composition range and that the critical temperature of the B2/L2_1 order-disorder transformation in the Fe_3Ga-Ni_3Ga pseudo-binary section gradually increases with increasing Ni content. The existing composition region of the martensite phase at room temperature was also determined by the diffusion triple method.
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Solder balls were attached to the Cu/Ni-P/Au metallized BGA substrate. The two solder ball used in this study are Sn-3.2Ag-0.5Cu and Sn-3-5Ag-0.5Cu-0.07Ni-0.01Ge. The package was subjected to thermal aging at 150 deg C for 100-100...
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Solder balls were attached to the Cu/Ni-P/Au metallized BGA substrate. The two solder ball used in this study are Sn-3.2Ag-0.5Cu and Sn-3-5Ag-0.5Cu-0.07Ni-0.01Ge. The package was subjected to thermal aging at 150 deg C for 100-1000 h in order to investigate IMC formation behavior. Cross sections and the surface of the IMC layer, revealed through etching of the unreacted solder, were inspected and analyzed with SEM and EDX. The IMCs mainly consist of two morphologies, hexagonal and whisker. The hexagonal crystal was identified as (Cu, Ni)_6Sn_5 and the whisker crystal is (Ni, Cu)_3Sn_4. The dissolution of Ni in Cu_6Sn_5 results in a synergistic effect that enhances the growth of the compound, and a similar effect was not observed when dissolved Cu was present in Ni_3Sn_4. This phenomenon is possibly due to the vacant energy band of the 3d-orbital of Ni. Ag_3Sn was also detected in the solder region near the interfacial IMC. The Ag_3Sn was not in direct contact with the BGA substrate.
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