Correlation between Microstructure and Mechanical Properties of Heat-Treated Ti–6Al–4V with Fe Alloying

The microstructure and mechanical properties of a newly developed Fe-microalloyed Ti–6Al–4V titanium alloy were investigated after different heat treatments. The volume fraction and the morphological features of the lamellar α phase had significant effects on the alloy’s mechanical performance. A dataset showing the relationship between microstructural features and tensile strength, elongation, and fracture toughness was developed. A high aging temperature resulted in high plasticity and fracture toughness, but relatively low strength. The high strength favored the fine α and the slender β. The high aspect ratio of lamellar α led to high strength but low fracture toughness. The alloy with ~84 vol % α exhibited the highest strength and lowest fracture toughness because the area of its α/β-phase interface was the highest. Optimal comprehensive mechanical performance and heat-treatment procedures were thus obtained from the dataset. Optimal tensile strength, yield strength, elongation, and fracture toughness were 999 and 919 MPa, 10.4%, and 94.4 MPa·m1/2, respectively.

High Strain Rate Mechanical Properties of SAC-Q With Sustained Elevated Temperature Storage at 100 °C

Leadfree electronics in harsh environments often may be exposed to elevated temperature for the duration of storage, transport, and usage in addition to high strain rate triggering loads during drop-impact, vibration, and shock. These electronic components may get exposed to high strain rates of 1 to 100 s−1 and operating temperatures up to 200 °C in critical surroundings. Doped SAC solder alloys such as SAC-Q are being considered for use in fine-pitch electronic components. SAC-Q consists of Sn-Ag-Cu alloy in addition to Bi (SAC+Bi). Prior data presented to date for lead-free solders, such as SAC-Q alloy, at high aging temperature and high strain rate are for 50 °C sustained exposure. In this paper, the effect of sustained exposure to temperature of 100 °C on high strain rate properties of SAC-Q is studied. Thermally aged SAC-Q samples at 100 °C have been tested at a range of strain rates including 10, 35, 50, and 75 s−1 and operating temperatures ranging from 25 °C up to 200 °C. Stress–strain curves are established for the given range of strain rates and operating temperatures. Also, the computed experimental results and data have been fitted to the Anand viscoplasticity model for SAC-Q for comparison.

Ethylene Oligomerization over Nickel Supported Silica-Alumina Catalysts with High Selectivity for C10+ Products

The nickel (II) loading silica-alumina under various treatments in terms of aging temperature, Si/Al ratio and activation temperature were investigated by XRD, N2 adsorption-desorption, TEM, UV-Vis, NH3-TPD and XRF and then applied to catalyze the ethylene oligomerization. High aging temperature, low Si/Al ratio and high activation temperature were beneficial to high selectivity for C10+ products because of a reasonable match between Ni active sites and acid sites, high Ni loading content and less octahedral coordination Ni2+ species, respectively. Ni loading content was more important than the number of acid sites for high yield of C10+ products, and less octahedral coordination Ni2+ species favored less by-products produced at high reaction temperature. In addition, other experimental conditions, such as reaction temperature, weight hourly space velocity (WHSV) and nickel precursor were discussed in the paper.

High Strain Rate Mechanical Properties of SAC-Q With Sustained Elevated Temperature Storage at 100°C

Leadfree electronics in harsh environments may often be exposed to elevated temperature for the duration of storage, process and usage in addition to high strain rate triggering loads during drop-impact, vibration and shock. These electronic components may get exposed to high strain rates of 1 to 100 per seconds and operating temperature up to 200°C in the critical surroundings. SAC solder alloys (e.g. SAC-Q (CYCLOMAX), and Innolot) are being considered for use in fine-pitch electronic components. SAC-Q consists of Sn-Ag-Cu alloy in addition to Bi (SAC+Bi). The data presented till date for lead-free solders like SAC-Q alloy at high aging temperature and at high strain rate are for 50°C sustained exposure. In this paper, effect of sustained exposure of 100°C on high strain rate properties of SAC-Q is studied. Thermally aged SAC-Q samples at 100°C have been tested at a range of strain rates including 10, 35, 50, and 75 per second and operating temperatures starting from 25°C up to 200°C. Stress-strain curves are established for the given range of strain rates and operating temperatures. Also, the computed experimental results and data have been fit to the Anand Viscoplasticity model for SAC-Q for comparison.

Formation of Kirkendall Voids at Low and High Aging Temperature in the Sn-0.7Cu-1.0wt.%Si3N4/Cu Solder Joints

The intermetallic compounds (IMCs) layer formed between Sn-0.7Cu-1.0wt.%Si3N4(SC-1.0SN) solder and Cu-substrate were investigated through isothermal solid-state aging. The SC-1.0SN/Cu solder joints were aged at 50°C and 150°C for 24h, 240h, 480h and 720h duration after reflow. The as-soldered joint IMC formed at interface was Cu6Sn5. In addition, only Cu6Sn5layer was observed at the interface of the samples aged at low temperature of 50°C although the aging duration was prolonged up to 720h and has begun to increase in thickness. On the other hand, the Cu3Sn layer was clearly observed in the sample of aged at 150°C up to 240h. However, at least no voids were vividly observed in the 50°C aged samples, while kirkendall voids were clearly found in Cu3Sn layer of samples aged at 150°C up to 480h of aging time will be discussed further.

Low and High Temperature Isothermal Aging Effect on Morphology and Diffusion Kinetics of Intermetallic Compound (IMC) for Sn-Cu-Si3N4 Composite Solder

The effect of excessive intermetallic growth to the reliability of solder joints become major problem in electronic devices industry. In this study, we used Sn-Cu-Si3N4composite solder to observe the intermetallic compound (IMC) growth during low and high temperature aging. 50°C and 150°C represent low and high aging temperature respectively. Various isothermal of aging times were carried out by using 24hrs, 240hrs and 720hrs. The IMC thickness increases with increasing of aging temperature and time. Cu6Sn5 phase appear at low aging temperature whilst Cu6Sn5together with Cu3Sn phases has been observed at high aging temperature. The growth kinetics for low and high aging temperature is 1.63x10-18μm2/s and 2.75 x10-18μm2/s.

Effect of Post Weld Heat Treatment on Fusion and Heat Affected Zone Microstructure and Mechanical Properties of Inconel X-750 Welds

The Inconel X-750 indicates good hot corrosion resistance, high stability and strength at high temperatures and for this reason the alloy is used in manufacturing of gas turbine hot components. The objective of this research was study the effect of post weld heat treatment (PWHT) on fusion zone and heat affected zone microstructure and mechanical properties of Inconel X-750 weld. After welding, samples were solutionized at 1500 0C. Various aging temperature and times were studied. The results show that aging temperature and time during PWHT can greatly affect microstructure and hardness in fusion zone and heat affected zone. As high aging temperature was used, the grain size also increased and M23C6 at the grain boundary decreased. This can result in decreased of hardness. Moreover excessive aging temperature can result in increasing MC carbide intensity in parent phase (austenite). It can also be observed that M23C6 at the grain boundary decreased due to high aging temperature. This resulted in decreasing of hardness of weld metal and heat affected zone. Experimental results showed that the aging temperature 705 0C aging time of 24 hours provided smaller grain size, suitable size and intensity of MC carbide resulting in higher hardness both in weld metal and HAZ.