Effects of Yttrium on Cyclic Oxidation Resistance of Co-10Cr-5Al Alloy

2013 ◽  
Vol 785-786 ◽  
pp. 844-847
Author(s):  
Jun Huai Xiang ◽  
Xian Chao Xu ◽  
Ling Yun Bai ◽  
Yun Xiang Zheng ◽  
Huai Shu Zhang
Keyword(s):  
Oxidation Resistance ◽  
Oxidation Kinetics ◽  
Oxidation Rate ◽  
Cyclic Oxidation ◽  
Oxidation Behavior ◽  
Oxidation Process ◽  
Local Zone ◽  
Rate Law ◽  
Parabolic Rate

The cyclic oxidation behavior of Co-10Cr-5Al alloys with and without Y in atmosphere at 800 °C was investigated. The addition of 0.3 at.% Y increased the oxidation rate of the alloy and changed the behavior from irregular oxidation kinetics to approximate parabolic rate law. The scales grown the alloys with and without Y were both composed of an outer Co2O3layer and an inner complex layer of Al2O3, Co2O3and Cr2O3, except that the addition of Y impaired the adhesion of the scale. Over-doped Y agglomerated in local zone plays an adverse role in the oxidation process by accelerating the oxidation rate.

Effects of Yttrium on Cyclic Oxidation Resistance of Co-10Cr-5Al Alloy at 700 °C

2014 ◽  
Vol 528 ◽  
pp. 25-29
Author(s):  
Ling Yun Bai ◽  
Xian Chao Xu ◽  
Jun Huai Xiang ◽  
Yun Xiang Zheng ◽  
Jun Wang
Keyword(s):  
Oxide Scale ◽  
Oxidation Resistance ◽  
Oxidation Rate ◽  
Cyclic Oxidation ◽  
Oxidation Behavior ◽  
Adhesive Property ◽  
Complex Mode ◽  
Rate Law ◽  
Parabolic Rate

The cyclic oxidation behavior of Co-10Cr-5Al alloys in atmosphere at 700 °C was investigated. The addition of 0.3 at.% Y changed the oxidation behavior from the approximate parabolic rate law to complex mode. The scale grown on the surface of Co-10Cr-5Al cracked seriously, while the oxide scale the Y doped alloy had better adhesive property. Yttrium doped in the sample promoted the forming of continuous Al2O3layer and decreased the oxidation rate of Co-10Cr-5Al alloys.

Cyclic Oxidation Resistance of Co-10Cr-5Al-0.3Y Alloy at 800 oc

2014 ◽  
Vol 1015 ◽  
pp. 505-508
Author(s):  
Ling Yun Bai ◽  
Hong Hua Zhang ◽  
Huai Shu Zhang ◽  
Yun Xiang Zheng ◽  
Jun Huai Xiang
Keyword(s):  
Oxidation Resistance ◽  
Oxidation Rate ◽  
Cyclic Oxidation ◽  
Oxidation Behavior ◽  
Oxidation Process ◽  
Oxidation Mechanism ◽  
Local Zone

The cyclic oxidation behavior of Co-10Cr-5Al alloys with and without 0.3 at% Y doped in atmosphere at 800oC was investigated. The addition of 0.3 at.% Y increased the oxidation rate of the alloy and changed the oxidation mechanism. The scales grown the alloys with and without Y were both composed of an outer Co2O3layer and an inner complex layer of Al2O3, Co2O3and Cr2O3, except that the addition of 0.3 at% Y enhanced the adhesion of the scale. 0.3 at% Y agglomerated in local zone which accelerated the oxidation rate and was not conductive to the oxidation process of the Co-10Cr-5Al alloy.

Effect of Yttrium Addition on High Temperature Oxidation Resistance of Co-10Cr-5Al Alloys

2011 ◽  
Vol 391-392 ◽  
pp. 606-610 ◽  
Author(s):  
Huai Shu Zhang ◽  
Hong Hua Zhang ◽  
Jun Huai Xiang ◽  
Shan Wang ◽  
Di Wu
Keyword(s):  
High Temperature ◽  
Oxidation Resistance ◽  
Oxidation Rate ◽  
High Temperature Oxidation ◽  
Oxidation Behavior ◽  
Temperature Oxidation ◽  
Linear Rate ◽  
Rate Law ◽  
Yttrium Addition ◽  
Parabolic Rate

The oxidation behavior of Co-10Cr-5Al-0.3Y alloy in 1 atm of pure O2 at 700°C was investigated. The addition of 0.3 at.%Y significantly increased the oxidation rate of the alloy and changed the oxidation behavior from the approximate parabolic rate law to linear rate law. The scale grown on the surface at 700°C was porous with many small voids and cracks, and was composed of an outer CoO layer and an inner complex layer rich in Al2O3 and Cr2O3 which were intermingled with yttric oxide and spinel Co(Cr, Al)2O4.

scholarly journals Additively Manufactured NiTi and NiTiHf Alloys: Estimating Service Life in High-Temperature Oxidation

Materials ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2104 ◽  
Author(s):  
Hediyeh Dabbaghi ◽  
Keyvan Safaei ◽  
Mohammadreza Nematollahi ◽  
Parisa Bayati ◽  
Mohammad Elahinia
Keyword(s):  
High Temperature ◽  
Oxidation Rate ◽  
High Temperature Oxidation ◽  
Oxidation Behavior ◽  
Early Stage ◽  
Niti Alloy ◽  
Temperature Oxidation ◽  
X Ray ◽  
Rate Law ◽  
Parabolic Rate

In this study, the effect of the addition of Hf on the oxidation behavior of NiTi alloy, which was processed using additive manufacturing and casting, is studied. Thermogravimetric analyses (TGA) were performed at the temperature of 500, 800, and 900 °C to assess the isothermal and dynamic oxidation behavior of the Ni50.4Ti29.6Hf20 at.% alloys for 75 h in dry air. After oxidation, X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy were used to analyze the oxide scale formed on the surface of the samples during the high-temperature oxidation. Two stages of oxidation were observed for the NiTiHf samples, an increasing oxidation rate during the early stage of oxidation followed by a lower oxidation rate after approximately 10 h. The isothermal oxidation curves were well matched with a logarithmic rate law in the initial stage and then by parabolic rate law for the next stage. The formation of multi-layered oxide was observed for NiTiHf, which consists of Ti oxide, Hf oxide, and NiTiO3. For the binary alloys, results show that by increasing the temperature, the oxidation rate increased significantly and fitted with parabolic rate law. Activation energy of 175.25 kJ/mol for additively manufactured (AM) NiTi and 60.634 kJ/mol for AM NiTiHf was obtained.

Air Oxidation of Porous Cu-35wt.%Ni-(5,10,15) wt%Cr Alloys at 650°C

2013 ◽  
Vol 365-366 ◽  
pp. 987-990
Author(s):  
Jian Chen ◽  
Zi Han Huang ◽  
Yan Jie Ren ◽  
Wen Wen ◽  
Xiang Wu Xiao ◽  
...  
Keyword(s):  
Oxidation Rate ◽  
Oxidation Behavior ◽  
Air Oxidation ◽  
Internal Oxide ◽  
Rate Law ◽  
Cr Content ◽  
Ni Content ◽  
Initial Stage ◽  
Parabolic Rate

The oxidation behavior of porous Cu-Ni-Cr alloys containing approximately 5,10 and 15 wt.%Cr, but with a similar Ni content of 35 wt.%, was studied at 650°C in air. The results showed that the oxidation of alloys follows linear law at initial stage and then the parabolic rate law. Continuous external scales of CuO and Cu2O formed on the alloys. Some internal oxide of were observed. In addition, with increase of Cr content, the oxidation rate decreased slightly.

Oxidation Kinetics of Self-Lubricating Ti-48%Al-2%Nb-2%Cr-x%CaF2 Composites

2011 ◽  
Vol 121-126 ◽  
pp. 288-292
Author(s):  
Li Ying Yang ◽  
Shou Ren Wang ◽  
Ying Zi Wang ◽  
Ru Ma ◽  
Yong Wang
Keyword(s):  
Oxidation Resistance ◽  
Oxidation Kinetics ◽  
Solid Lubricant ◽  
Important Influence ◽  
Rate Law ◽  
Parabolic Rate ◽  
Kinetics Of

The Oxidation kinetics of Ti-48Al-2Nb-2Cr composites (TANC) with addition of different weight contents of CaF2 solid lubricant was evaluated. It is indicated that oxidation dynamic curve follow quasi-parabolic rate law under 800 °C. Once the temperature exceed 1100 °C, the oxidation dynamic curve seems to do not follow quasi-parabolic rate law. The contents of solid lubricant in TANC matrix occur an important influence for oxidation resistance

Effects of Yttrium on Cyclic Oxidation Resistance of Co-10Cr-5Si Alloy

2013 ◽  
Vol 785-786 ◽  
pp. 914-917
Author(s):  
Jun Huai Xiang ◽  
Xian Chao Xu ◽  
Ling Yun Bai ◽  
Yun Xiang Zheng ◽  
Huai Shu Zhang
Keyword(s):  
Oxidation Resistance ◽  
Rate Constant ◽  
Cyclic Oxidation ◽  
Oxidation Behavior ◽  
Parabolic Rate Constant ◽  
Cooling Process ◽  
Parabolic Rate

The cyclic oxidation behavior of Co-10Cr-5Si alloys with and without Y in atmosphere at 800 °C was investigated. The addition of 0.3 at.% Y decreased the average parabolic rate constant from 4.45×10-10g2cm-2s-1to 3.58×10-10g2cm-2s-1. The thin scales grown on Co-10Cr-5Si alloys were mainly composed of an outer CoO layer, followed by an inner protective SiO2layer. However, the scales can not be observed for Co-10Cr-5Si-0.3Y alloy, probably due to the spallation of the scales during the cooling process. The addition of 0.3 at.% Y improved the cyclic oxidation resistance of the Co-10Cr-5Al alloy.

Effects of Yttrium on Cyclic Oxidation Resistance of Co-10Cr-5Si Alloy at 700 °C

2014 ◽  
Vol 525 ◽  
pp. 154-157
Author(s):  
Jun Huai Xiang ◽  
Xian Chao Xu ◽  
Ling Yun Bai ◽  
Yun Xiang Zheng ◽  
Huai Shu Zhang
Keyword(s):  
Oxidation Resistance ◽  
Rate Constant ◽  
Cyclic Oxidation ◽  
Oxidation Behavior ◽  
Parabolic Rate Constant ◽  
Parabolic Rate

The cyclic oxidation behavior of Co-10Cr-5Si alloys with and without Y in atmosphere at 700 °C was investigated. The addition of 0.3 at.% Y decreased the average parabolic rate constant from 4.39×10-10g2cm-2s-1to 3.42×10-10g2cm-2s-1. The surface components with and without Y were both composed of an outer CoO and inner protective SiO2. There were more SiO2formed when Y doped into the alloy. The addition of 0.3 at.% Y improved the cyclic oxidation resistance of the Co-10Cr-5Al alloy.

Effect of Y on Cyclic Oxidation Behavior of FeCrNi Heat-Resisting Steel

2012 ◽  
Vol 557-559 ◽  
pp. 170-174
Author(s):  
Xiao Liu ◽  
Long Mei Wang
Keyword(s):  
Silicon Dioxide ◽  
Oxidation Resistance ◽  
Internal Oxidation ◽  
Oxidation Rate ◽  
Cyclic Oxidation ◽  
Oxidation Behavior ◽  
Experimental Sample ◽  
Oxidation Layer ◽  
Pinning Effect

The oxidation resistance of FeCrNi heat-resisting steel at 1150°C and 1200°C is analyzed and studied using XRD, SEM and EDS techniques. The results show that the oxidation resistance of the heat-resisting steel is improved remarkably after adding yttrium. The value of oxidation rate of experimental Sample 1 (without adding Y) is 3.25 times and 1.56 times higher than Sample 2, respectively at 1150°C and 1200°C after oxidizeing for totally 144h. On the surface of the heat-resisting steel containing Y, the dense and adherent Cr2O3 scale and FeCr2O4 scale are formed and played the protection role. In the internal oxidation layer, the pinning effect of silicon dioxide is strengthened by Y, and Y has a pining effect directly.

scholarly journals High-Temperature Oxidation Kinetics of Additively Manufactured NiTiHf

2020 ◽  
Author(s):  
Hediyeh Dabbaghi ◽  
Mohammadreza Nematollahi ◽  
Keyvan Safaei Baghbaderani ◽  
Parisa Bayatimalayeri ◽  
Mohammad Elahinia
Keyword(s):  
High Temperature ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Oxidation Kinetics ◽  
Oxidation Rate ◽  
Oxidation Behavior ◽  
Transformation Temperatures ◽  
X Ray ◽  
Rate Law ◽  
Kinetics Of

Abstract NiTi-based high-temperature shape memory alloys (HTSMAs) such as NiTiHf have been utilized in a broad range of applications due to their high strength and work output, as well as, their ability to increase the transformation temperatures (TTs). Recently, additive manufacturing techniques (AM) have been widely used to fabricate complex shape memory alloy components without any major modifications or tooling and has paved the way to tailor the manufacturing and fabrications of microstructure and critical properties of their final parts. NiTi alloys properties such as transformation temperatures can be significantly altered due to oxidation, which can occur during the manufacturing process or post-processing. In this work, the oxidation behavior of Ni-rich NiTi20Hf shape memory alloys, which was fabricated by the selective laser melting (SLM) method, is evaluated. Thermogravimetric analysis (TGA) is used to assess the kinetic behavior of the oxidation at different temperature ranges of 500, 700, and 900 °C for 20 hours in the air. After oxidation, to evaluate the microstructure and chemical composition X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) was conducted. The isothermal oxidation kinetics of conventional NiTi20Hf alloys were studied, and the results were compared to AM samples. Results show a two-stage oxidation rate at which oxidation increased with the high rate at the initial stage. As the oxidation time increased, the oxidation rate gradually decreased. The oxidation behavior of NiTiHf alloys initially obeyed logarithmic rate law and then followed by parabolic rate law. SEM results showed the formation of a multi-layered oxide scale, including TiO2, NiTiO3, and Hf oxide.

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