Papers by Keyword: Al Addition

Abstract: The studies regard analysis of variable Al and Fe additions on the chosen group of CuSn alloys. The group of tin bronzes known and applied for thousands of years has still found its application in many branches of industry, however it was observed that small amounts of aluminum and iron may affect the original properties strongly. The changes of mechanical properties and microstructure is discussed in detail. Aside of many advantageous properties of these bronzes, it is noted that the mentioned alloying additions have beneficial effect on the gas-induced shrinkage porosity. Simultaneously, the effect of the aluminum addition on the characteristic phase transformation points was determined basing on the analysis of calorimetric curves. The results are correlated with microstructure observations.

Abstract: Fe-Si alloys with various concentration of Al (0, 1, 3 and 5 % by mass) were synthesized by a spark plasma sintering technique. The specimens were prepared in an evacuated chamber of less than 4 Pa and under compressive stress of 40 MPa. During spark discharge, the heating rate was fixed at 10°C/min. After the SPS process was completed, the specimen surfaces were ground with silicon carbide papers. The metallographic characterization was performed by mean of X-ray diffraction (XRD) and scanning electron microscope (SEM) equipped with energy dispersive X-ray (EDX) spectroscopy. According to sintering curves, all samples seem to have a similar sintering behavior. The densification of specimens was completed in the temperature range of about 1020-1050°C. Microstructure and phase characterization revealed that the alloys were mainly composed of FeSi₂ and FeSi phases containing oxide inclusions. The SEM images indicated that the fraction of FeSi phase and oxide inclusions appears to decrease with increase in Al concentration in the Fe-Si alloy.

Abstract: This research objective is to study the microstructural modification by Al additions in cast nickel base superalloy, GTD-111 by means of vacuum arc melting process. The Al additions to the alloy were 1, 2 and 3% by weight. After that, all casted specimens were performed with different reheat treatment conditions, which consist of solutioning temperatures of 1125°C, 1145°C, 1165°C, 1185°C and 1205°C, respectively, for 6 hours following with precipitation aging at 845°C for 24 hours. After all reheat treatments, the microstructures were investigated and analyzed by SEM. From all obtained results, it was founded that the specimens with Al additions for 1-2%wt. following with reheat treatment show the decrease in size of γ’ precipitated particles when increasing solutioning temperatures. 3%wt. of Al addition was too high content resulting in already improper microstructural characteristics. However all obtained data of area fractions of precipitate phase were almost the same. Effect of Al addition and solutioning temperature did not provide any significant effect in this case. The mechanical property behavior: hardness was investigated by using Vickers hardness tester. It was found that the hardness all was very similar and increased with higher solutioning temperatures.

Abstract: Traditional TRIP steels have been developed for several decades, however, when thestrength reaches 1000MPa, the elongation rate is difficult to be raised over 20%. In the light ofthermodynamics, phase diagram of TRIP steel containing rather high amount of Al is optimized andthe attractive function of Al, which largely increases carbon solubility in austenite is found. As highercarbon content leads to higher stability of austenite and better TRIP effect of TRIP steel, newcomposition of high strength TRIP steel with high amount Al is designed as well as heat treatmentprocesses. The newly developed TRIP steel exhibits superior mechanical properties and the productof its strength and plasticity is higher than 30000 MPa%, i.e., the target of the mechanical propertiesof 3th generation automotive steel.

Abstract: The effect of titanium and aluminum contents, strain, strain rate and tested temperatures on the mechanical properties and microstructural properties will be investigated in this study. These cobalt base super alloys are to be tested using material testing system (MTS) at strain rates of 10-3, 10-2 and 10-1s-1 and at temperatures of 700°C, 500°C and 25°C respectively. It is found that the flow stress increases with increasing strain rate and Ti and Al contents, but decreases with increasing temperature. Furthermore, the strain rate sensitivity increases with increasing strain rate, but decreases with increasing temperature. The microstructural observations confirm that the mechanical response of the cobalt superalloy specimens is directly related to the effects of the titanium and aluminum contents, strain rate and temperature on the evolution of the microstructure. It can be observed that the strengthening effect in cobalt suprealloy is a result primarily of dislocation multiplication. The dislocation density increases with increasing strain rate, but decreases with increasing temperature.

Abstract: In order to improve toughness of the weld heat affected zone (HAZ) of ultra-fine grained (UFG) steel, a thermal simulation procedure of Fe-Mn-Si UFG steels with different Al addition was conducted and the corresponding microstructure was characterized and investigated. The results indicate that the maximum value on driving force of nucleation is ultra-fine grain steel with wtAl=0.6%, it has been explained in Nucleation kinetics that the grains are fine in UFG2. On the other hand, the bainite ferrite growth orientation has been increased. The toughness was remarkably enhanced in the steel welded heat affected zone. The formation of strie retained austenite and grain refinement of bainite ferrite in Fe-Mn-Si UFG steels with Al additions results in the increasing toughness of weld HAZ.

Abstract: The Mg-Sn-Ca alloys have shown superior creep properties compared to the creep resistant alloy AE42. In the present study, the effects of small amounts of Al and Si additions on the mechanical properties have been investigated on a Mg-3Sn-2Ca (TX32) alloy. The Al content in the selected alloys was 0.4 wt% and the Si content was varied from 0–0.8 wt% in steps of 0.2 wt.%. The alloys were cast in pre-heated permanent molds. Cylindrical specimens machined from the cast billets were tested in compression in the temperature range 25–250 °C at a strain rate of 0.0001 s–1. The alloy with 0.4 wt% Al shows an increased strength at all test temperatures compared with the TX32 base alloy. This is attributed to a solid solution strengthening of Al in Mg. The alloy with 0.4 wt% Al and 0.2 wt% Si has compressive strength that is closer to that of the TX32 alloy. However, increased additions of Si (from 0.4–0.8 wt%) reduce the strength, more significantly at higher temperatures.