Astuty Amrin

Effect of solder volume on interfacial reaction between SAC405 solders and EN(B)EPIG surface finish

The electronic packaging industry is now being driven towards smaller, lighter, and thinner electronic products but with higher performance and more functions. Thus, smaller solder ball sizes are needed for fine solder joint interconnections to fulfill these requirements. This study investigates the interfacial reactions during reflow soldering and isothermal aging between Sn-4.0Ag-0.5Cu (SAC405) and electroless nickel (boron)/ immersion palladium/immersion gold (EN(B)EPIG). Reliability of solder joint has also been investigated by performing solid state isothermal aging at 125 °C for up to 2000 hours. The results revealed that after reflow soldering, (Cu, Ni)6Sn5 IMC is formed between solder and substrate while after aging treatment another IMC was found between (Cu, Ni)6Sn5 and substrate known as (Ni, Cu)3Sn4. Aging time of solder joints resulted in an increase in IMC thickness and a change in morphology into more spherical, dense and with larger grain size. By using optical microscope, the average thickness of the intermetallics was measured and it found that the larger solder balls produced thicker IMC than the smaller solder balls during reflow soldering. However, after aging the smaller solders produced thicker IMC than the larger solders.

Effect of heat treatment parameters on the microstructure and microhardness of Ti-6Al-4V alloy

Ti-6Al-4V is a dual-phase (α+β) Ti-alloy which possesses potential series and complex microstructures. The coexistence of β-phase alongside α-phase in Ti-6Al-4V alloy enhances the heat treatment process. Precise adjustments of heat treatment parameters can lead to diversity of microstructures that can be transformed from equiaxed to fully lamellar to bi-modal. These microstructures have a critical impact on the mechanical properties. This work investigates the effect of altering the heat treatment parameters on both the microstructure and microhardness of Ti-6Al-4V alloy to elucidate alloy’s behaviour on the basis of microstructure - properties relations. Recrystallization annealing, solution treatment followed by aging, and β-annealing were performed on several samples to obtain various microstructures. The as-received sample exhibited fine equiaxed structure with a grain size of 1.78 µm. Recrystallization annealing of the fine equiaxed structure yielded considerable grain growth, resulting 7.29 µm larger globular grains. The bi-modal microstructure was obtained from the equiaxed structure through solution treatment followed by aging. The application of β-annealing treatment resulted in a lamellar microstructure. The microhardness readings were affected by variations in the heat treatment procedures. The highest and lowest hardness were 386.1Hv and 302.2 Hv for the lamellar and the equiaxed microstructures, respectively. The improvement in the microhardness was 27.8%. In comparison, the bi-modal microstructure demonstrated a balanced hardness.Ti-6Al-4V is a dual-phase (α+β) Ti-alloy which possesses potential series and complex microstructures. The coexistence of β-phase alongside α-phase in Ti-6Al-4V alloy enhances the heat treatment process. Precise adjustments of heat treatment parameters can lead to diversity of microstructures that can be transformed from equiaxed to fully lamellar to bi-modal. These microstructures have a critical impact on the mechanical properties. This work investigates the effect of altering the heat treatment parameters on both the microstructure and microhardness of Ti-6Al-4V alloy to elucidate alloy’s behaviour on the basis of microstructure - properties relations. Recrystallization annealing, solution treatment followed by aging, and β-annealing were performed on several samples to obtain various microstructures. The as-received sample exhibited fine equiaxed structure with a grain size of 1.78 µm. Recrystallization annealing of the fine equiaxed structure yielded considerable grain growth, resulting 7.29 µm large...

Effect of Temperature on Oxide Growth Behaviour of Fe-33Ni-19Cr Alloy

The isothermal oxidation behaviour on two different temperature of Fe-33Ni-19Cr alloy was studied in this work. The present paper focuses on the isothermal oxidation behaviour at 700oC and 900oC. The oxidized samples were subjected to oxidation experiment under isothermal conditions for 500 hours. Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS) and X-Ray Diffraction (XRD) technique were employed in this study to analyse the oxidation behaviour of oxidized samples. The kinetics of oxidation followed the parabolic rate law which represent diffusion controlled oxide growth rate. Results indicate that Fe-33Ni-19Cr alloy oxidized at 700oC possess a better oxidation resistance with low Kp value of 2.39 x 10-7 mg2cm-4s-1. The oxide scale formed during oxidation were generally complex consists of several oxide phases. The samples morphologies of oxidized samples were influenced by the alloy structure and expose conditions. An elemental EDX line scan analysis of samples oxidized at 900oC indicated four different oxide layers composes of several oxide structure with evidence of internal oxide precipitates composed of Al-rich oxide phase.

Influence of Grain Size on the Isothermal Oxidation of Fe–40Ni–24Cr Alloy

The influence of grain size on the oxidation of Fe–40Ni–24Cr alloy was studied in this work. The present paper focuses on the isothermal oxidation behaviour at 700 °C. Solution treatment at three different temperatures, namely 950, 1050 and 1150 °C, was applied to Fe–40Ni–24Cr alloy to alter the average grain size of the samples. The results showed that the average grain size increased with increase in solution treatment temperature. Optical microscopy, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) were employed in this study to analyse the oxidation behaviour of solution-treated samples. The solution-treated samples were subjected to oxidation experiment under isothermal conditions for 500 h. The oxide scales formed during oxidation were generally complex, and their morphologies and structure were influenced by the alloy structure and expose conditions and environment. The kinetics of oxidation followed the parabolic law which represents diffusion-controlled oxide growth rate. After 500-h exposure, all alloy displayed protective oxidation with the fine grain samples exhibiting the lowest weight gain, hence the superior oxidation resistance. Smaller grain size improves the protective oxidation behaviour by enhancing exfoliation resistance and reducing oxidation rate.

Microstructural Study of Newly Designed Ti-6Al-1Fe Alloy through Deformation

Recently, iron (Fe) is introduced to substitute vanadium (V) in Ti-alloy. Therefore, new (α+β) titanium alloy, Ti-6Al-1Fe was designed through a complete replacement of V by Fe with major composition modifications of Ti-6Al-4V. This new alloy is believed could provide similar properties of Ti-6Al-4V through modification of its microstructures. Different heat treatments can lead to a diversity of microstructural permutations and combinations. Thus, it is very crucial to study in-depth understanding about the microstructure of Ti-6Al-1Fe. Results reveal that the microstructure of as-received alloy is a typical fine lamellar microstructure. The bi-modal microstructure can be obtained by hot rolling below beta-transus temperature (Tβ) followed by recrystallization treatment at 925°C. While cold rolling followed by recrystallization treatment at 925°C produce equiaxed microstructure.

Development of iron (Fe) additions approach for cost reduction in Ti-alloy - a review

Reduction of materials cost without sacrificing their functional properties is one of the main goals for materials engineers. This article focuses on Fe and its effect as an obvious example of introducing inexpensive alloying elements into Ti-alloys. It could also be a guide for future researches that would be aimed at replacing expensive β-stabiliser elements with inexpensive elements. Recently, more attention has been paid to low-cost Ti-alloys that contain Fe. This has resulted in the designing of many alloys such as Ti metal 62S and Ti-Fe-O-N Ti-alloys. This technical trend has been used to design new Ti-alloys with good mechanical features, such as Ti8LC and Ti-5.5Al-1Fe Ti-alloys in China and Japan respectively. Nowadays, major composition modifications of Ti-6Al-4V alloy have been proposed through the complete replacement of V by Fe. Three new alloys (Ti-6Al-xFe) are developed to investigate the effect of Fe additions on the microstructure and the mechanical properties.

Iron as a Promising Alloying Element for the Cost Reduction of Titanium Alloys: A Review

This article focuses on the effect of iron (Fe) addition on the fabrication of Ti-alloys. Fe is a potential inexpensive element that can be added to Ti-alloys to reduce their cost. This metal can also be used to replace expensive β-stabilizing alloying elements, such as vanadium (V) and molybdenum (Mo), for Ti-alloys. Fe has also been utilized as a novel cost-effective alloying element to decrease Ti-alloy costs and to design other alloys, such as Ti metal 62S (Ti-6Al-1.7Fe-0.1Si) and Ti-Fe-O-N Ti-alloy. This technical perspective has been further applied to fabricate new Ti-alloys. For example, Ti8LC and Ti-5.5Al-1Fe with good mechanical features have been developed as novel Ti-alloys in China and Japan, respectively. Nowadays, vanadium (V) of Ti-6Al-4V alloy is completely replaced with Fe to produce Ti-Al-Fe alloy series. Three new alloys, namely, Ti-6Al-xFe, where x = 1, 2, and 3 wt%, are introduced to examine the effect of Fe addition on the microstructure and mechanical properties of Ti-alloys.

Microstructures and Hardness of Newly Designed Ti-6Al-(1-3)Fe Alloys

Many Ti-alloys were designed by introducing iron (Fe) as an alloying element to improve the mechanical properties and reduce the cost of the alloys. Therefore, new (α+β) titanium alloys, Ti-6Al-(1-3)Fe were developed through complete replacement of vanadium (V) by iron with major composition modifications of Ti–6Al–4V, which is commonly used for aerospace applications. Ti-Al-Fe alloys were melted through vacuum arc melting technique followed by hot rolling. This study aims to investigate the effect of Fe addition on the microstructure and hardness of emerging (Ti-Al-Fe) alloys in comparison with Ti-6Al-4V alloy. Results reveal that the microstructures are typical lamellar structures, and the hardness ranges from 32 to 40.7 HRC. The hardness of the investigated alloys increases with increasing Fe content.

Grain Size Effects on the Oxidation of Fe-33Ni-19Cr Alloy at 700°C

The effect of different grain size on the oxidation of Fe-33Ni-19Cr alloy was discussed. The present paper focuses on the oxidation behaviour in dry air at temperature of 700oC with respect to oxidation kinetics. Solution treatment was applied to Fe-33Ni-19Cr alloy by means of different solution annealing temperature to alter the average grain size of the specimens. Solution heat treatments were carried out on Fe-Ni-Cr alloys at three different temperatures, namely, 1000oC, 1100oC and 1200oC. The results showed that the average grain size increased with increase in solution annealing temperature that was significantly affecting the oxidation kinetic of the materials. Optical microscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) were employed in this study to analyse the oxidation behaviour of solution-annealed samples. Smaller grain size improves the protective oxidation behaviour by enhancing spallation resistance and reducing oxidation rate. Spallation resistance correlates with a reduction in texture of the oxide layers.

Effect of grain size on the isothermal oxidation of Fe-33NI-19CR alloys at 700 °C

The isothermal oxidation behavior of two different grain size of Fe-33Ni-19Cr alloys was investigated at 700 °C in laboratory air. Different grain size of alloyed was made of solution annealing treatment at different temperatures, namely, 1050 °C and 1150 °C for fine and coarse grain, respectively. Optical microscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) were employed in this study to analyze the oxidation behavior of solution-annealed samples. Results indicate that the fine grain size solution-annealed alloys possess a better oxidation resistance and reduced oxidation rate than the coarse grain. The differences observed are attributed to the finer grains increasing the relaxation of the oxide scale stress and improving the adhesion of the oxide layer on the matrix.