Overview of transient liquid phase and partial transient liquid phase bonding

Transient liquid phase (TLP) bonding is a relatively new bonding process that joins materials using an interlayer. On heating, the interlayer melts and the interlayer element (or a constituent of an alloy interlayer) diffuses into the substrate materials, causing isothermal solidification. The result of this process is a bond that has a higher melting point than the bonding temperature. This bonding process has found many applications, most notably the joining and repair of Ni-based superalloy components. This article reviews important aspects of TLP bonding, such as kinetics of the process, experimental details (bonding time, interlayer thickness and format, and optimal bonding temperature), and advantages and disadvantages of the process. A wide range of materials that TLP bonding has been applied to is also presented. Partial transient liquid phase (PTLP) bonding is a variant of TLP bonding that is typically used to join ceramics. PTLP bonding requires an interlayer composed of multiple layers; the most common bond setup consists of a thick refractory core sandwiched by thin, lower-melting layers on each side. This article explains how the experimental details and bonding kinetics of PTLP bonding differ from TLP bonding. Also, a range of materials that have been joined by PTLP bonding is presented.

O–Cu(001): I. BINDING THE SIGNATURES OF LEED, STM AND PES IN A BOND-FORMING WAY

This work consists of two sequential parts, which review the advances in uncovering the capacity of VLEED, STM and PES in revealing the nature and kinetics of oxidation bonding and its consequences for the behavior of atoms and valence electrons at a surface; and in quantifying the O–Cu(001) bonding kinetics. The first part describes the model in terms of bond making and its effect on the valence DOS and on the surface potential barrier (SPB) for surfaces with chemisorbed oxygen. One can replace the hydrogen in a H 2 O molecule with an arbitrary less electronegative element and extend the M 2 O to a solid surface with Goldschmidt contraction of the bond length, which formulates a specific oxidation surface with identification of atomic valences and their correpondence to the STM and PES signatures. As consequences of bond making, oxygen derives foou additional DOS features in the valence band and above, i.e. O–M bonding (~ -5 eV), oxygen nonbounding lone pairs (~ - 2 eV), holes (≤ EF ), and antibonding metal dipoles (≥ EF ), in addition to the hydrogen-bond-like formation. The evolution of O -1 to O -2 transforms the CuO 2 pairing off-centered pyramid in the c(2× 2)-2 O -1 into the CU 3 O 2 pairing tetrahedron in the [Formula: see text] phase on the Cu(001) surface. The new decoding technique has enabled the model to be justified and hence the capacity of VLEED, PES and STM to be fully uncovered in determining simultaneously the bond geometry, the SPB, the valence DOS, and their interdependence.