The climb-controlled dislocation creep behavior was investigated in Mg–Al–Zn alloys of AZ31, AZ61 and AZ91 with different aluminum contents. The flow stress increased with the increase of aluminum content under the same deformation conditions. At high temperatures, the stress exponent was 5 and the activation energy was close to that for lattice diffusion of magnesium, whereas at low temperatures the stress exponent was 7 and activation energy was close to that for pipe diffusion for all alloys. By incorporating the effective diffusion coefficient and stacking fault energy into a constitutive equation, the dislocation creep behavior of magnesium alloys can be described by a single relation.

Dislocation creep behavior in Mg–Al–Zn alloys

Steady state flow of the FeCoNiCrMn high entropy alloy at elevated temperatures

Deformation mechanism in a coarse-grained Mg–Al–Zn alloy at elevated temperatures

A review on thermal cycling and drop impact reliability of SAC solder joint in portable electronic products

Forming of aluminum alloys at elevated temperatures – Part 1: Material characterization

Creep fracture behavior has been studied in Al-Mg and Al-Mg-Mn alloys undergoing solute-drag creep and in microduplex stainless steel undergoing both solute-drag creep and superplastic deformation. Failure in these materials is found to be controlled by two mechanisms, neck formation and cavitation. The mechanism of creep fracture during solute-drag creep in Al-Mg is found to change from necking-controlled fracture to cavitation-controlled fracture as Mn content is increased. Binary Al-Mg material fails by neck formation during solute-drag creep, and cavities are formed primarily in the neck region due to high hydrostatic stresses. Ternary alloys of Al-Mg- Mn containing 0.25 and 0.50 wt % Mn exhibit more uniform cavitation, with the 0.50 Mn alloy clearly failing by cavity interlinkage. Failure in the microduplex stainless steel is dominated by neck formation during solute-drag creep deformation but is controlled by cavity growth and interlinkage during superplastic deformation. Cavitation was measured at several strains, and found to increase as an exponential function of strain. An important aspect of cavity growth in the stainless steel is the long latency time before significant cavitation occurs. For a short latency period, cavitation acts to significantly reduce ductility below that allowed by neck growth alone. This effect is most pronounced in materials with a high strain-rate sensitivity, for which neck growth occurs very slowly.

/pdf/creep-fracture-during-solute-drag-creep-and-superplastic-2bpovjtg2w.pdf

Creep fracture during solute-drag creep and superplastic deformation

This chapter contains sections titled: Introduction Aerospace/Military Consortia Lead-Free Control Plans for Aerospace/Military Electronics Aerospace/Military Lead-Free Reliability Concerns Summary and Conclusions References

LeadFree Reliability in Aerospace/Military Environments

Recently, the industry has seen the development of a wide range of new Pb-free alloys. A significant element of uncertainty within the industry regarding these new alloys is the lack of defined data requirements for alloy acceptance. This paper describes the progress of recent efforts to standardize Pb-free solder alloy testing requirements. Hewlett-Packard, the iNEMI consortium, the Solder Products Value Council, and the IPC are working together to create such standards. To facilitate the standardization of alloy testing, the required tests are divided into three major areas, each of which may be covered by a separate standard. • Material properties • Solder joint reliability • Impact to manufacturing processes This paper presents the status of standardization efforts in each of these three areas.

/pdf/progress-in-developing-industry-standard-test-requirements-3op7rgsaj3.pdf

Progress in Developing Industry Standard Test Requirements for Pb-Free Solder Alloys

The industry has seen the development of a wide range of new Pb-free BGA ball alloys A significant element of uncertainty regarding these new alloys is the lack of defined data requirements for alloy acceptance This paper describes recent efforts at Hewlett-Packard to develop Pb-free solder alloy testing requirements To facilitate the standardization of alloy testing, the required tests are divided into three major areas • Material properties • Solder joint reliability • Impact to manufacturing processes This paper presents the approach to assess the risk of using new Pb-free BGA ball alloys on printed circuit assemblies

Gregory Henshall

Papers

Creep fracture during solute-drag creep and superplastic deformation

LeadFree Reliability in Aerospace/Military Environments

Progress in Developing Industry Standard Test Requirements for Pb-Free Solder Alloys

Acceptance testing of BGA ball alloys

Facet crystallography of fractured V(2.7 wt% Si) solid solution