P/M aluminum matrix composites: an overview

The structure of long period stacking/order Mg–Zn–RE phases with extended non-stoichiometry ranges

The effect of heat treatment on mechanical properties and corrosion behavior of AISI420 martensitic stainless steel

Corrosion of hot extrusion AZ91 magnesium alloy: I-relation between the microstructure and corrosion behavior

The creep response of solder joints in a microelectronic package, which are subjected to aggressive thermo-mechanical cycling (TMC) during service, often limits the reliability of the entire package. Furthermore, during TMC, the microstructures of the new lead-free solders (Sn–Ag and Sn–Ag–Cu) can undergo significant in situ strain-enhanced coarsening, resulting in in-service evolution of the creep behavior. In this paper, the coarsening kinetics of Ag 3 Sn particles in SnAg-based solder are studied, and the results are correlated with impression creep data from individual microelectronic solder balls subjected to thermal aging treatments. Coarsening influences creep behavior in two ways. At low stresses, the creep rate increases proportionately with precipitate size. At high stresses, precipitate coarsening influences creep response by altering the threshold stress for particle-limited creep. Based on these observations, a microstructurally adaptive creep model for solder interconnects undergoing in situ coarsening is presented.

Effect of thermo-mechanically induced microstructural coarsening on the evolution of creep response of SnAg-based microelectronic solders

Heat treatment parameters closely control the amount of carbides in steels. In this study, the influence of three parameters (heating temperature, heating rate and cooling rate) on the area percentage of M23C6-type carbides in the quenching microstructures of 0.45C–13Cr martensitic stainless steel has been studied. The experimental results obtained in this study demonstrate that the amount of carbides in the quenching microstructures of this steel can be severely modified through the heating and cooling conditions of the heat treatment.

Control of M23C6 carbides in 0.45C–13Cr martensitic stainless steel by means of three representative heat treatment parameters

The mechanical properties of tin have been studied by tensile tests in the temperature range 293–463 K. Tensile tests were performed for cylindrical samples at a constant strain rate and varying strain rates during deformation. In-situ-tensile tests also were conducted in ribbon-form samples. At the strain rates studied, deformation takes place preferentially by slip, although some scattered twins also were observed at lower temperatures. Strong grain growth occurs at the higher temperatures. Microstructural observations of deformed samples show that dynamic recrystallization is not important in the temperature range investigated. The fracture surface of the cylindrical samples changes from a chisel type of fracture at the lower temperatures to a simple shear type of fracture at the higher temperatures. Both the tensile strength and ductility decrease with increasing temperature. An explanation is given for the loss of ductility at high temperatures. The activation energy for creep, obtained from strain-rate-change tests is 35 kJ mol−1 and the stress exponent is about 6. These values are related to a slip mechanism controlled by pipe diffusion.

Microstructure and high temperature mechanical properties of tin

Using the dilatometry technique, γ→α transformation kinetics has been determined at different cooling rates in a steel with low carbon and low niobium contents (0.09 and 0.017 mass% respectively). First of all the real and the conventional transformation temperatures of the steel were determined. The real start temperature for proeutectoid ferrite formation (A' r3 ) corresponds to the point where the dilatometric curve starts to diverge from the straight during cooling. The conventional start and finish temperatures for proeutectoid ferrite formation (A r3 and A r1 ) are given by two points close to the minimum and the first maximum of the curve, respectively. The real start and finish eutectoid transformation temperatures -(A' r1 ) s and (A' r1 ) f - correspond to the second point of inflection and a point close to the second relative maximum of the curve, respectively. Carbon enrichment of the remaining austenite, as the transformation to ferrite advances, is corrected taking into account the dependence on the carbon content of the atomic volume of austenite. On the other hand, the dilatometric data have also been corrected with regard to the different expansion coefficients of austenite and ferrite. In this way it has been seen that the lever-rule method applied to the dilatometric curve is useful for determining transformation temperatures, but not for determining transformation kinetics, since the amount of proeutectoid ferrite calculated with this method was up to 10% greater than the real amount measured with an image analyser. Finally a model based on Avrami's law has been developed for the real γ→α transformation kinetics.

http://digital.csic.es/bitstream/10261/46233/3/05_ISIJ%20Int%2043%20_2003_%201228-1237.pdf

G. Caruana

Papers

Control of M23C6 carbides in 0.45C–13Cr martensitic stainless steel by means of three representative heat treatment parameters

Microstructure and high temperature mechanical properties of tin

Modelling of Phase Transformation Kinetics by Correction of Dilatometry Results for a Ferritic Nb-microalloyed Steel

Thermal stability of an composite processed by powder metallurgy

Effect of extrusion temperature on the microstructure and plastic deformation of PM-AZ92