Effect of Powder Morphology and Chemical Distribution on Properties of Multicomponent Alloys Produced Via Powder Metallurgy

Seungjin Nam,Se Eun Shin,Jae‑Hun Kim,Hyunjoo Choi 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.9

In this study, effects of morphology and chemical distribution of powder on mechanical properties was investigated inAl0.5CoCrCuFeNihigh-entropy alloys produced via powder metallurgy. At the early stages of ball-milling, Cr-deficientlarge powder is flattened, while Cr-rich powder is fractured to small particles because of the flattening of ductile particlesand fragmentation of hard particles at initial milling stage. However, with an increase in the milling duration, the Cr atomswere more uniformly distributed throughout the powders and the powders exhibited spherical shape with smooth surface. Moreover, as the ball-milling duration increased from 36 to 96 h, the Vickers hardness and compressive yield strength alsoincreased from 433 Hv0.5and 1166 MPa to 525 Hv0.5and 1739 MPa, respectively. This was attributed to the spherical powdersreducing as well as forming fine and uniform microstructures in sintered alloys. Also, the elemental uniformity suppressedthe formation of dendritic-unfavorable carbides.

방산 분야 텅스텐 합금 과립분말 개선 연구

지상용 한국산학기술학회 2020 한국산학기술학회논문지 Vol.21 No.10

Tungsten alloys are used widely in general industrial fields, but they are difficult to cast, so products are manufactured using powder metallurgy. In this study, a mixed powder of tungsten, nickel, and iron homogenized using a ball mill was added to pure water as a solvent, and PVA as a binder was added to prepare a spray drying mixture. The mixed liquid was prepared using a spraying machine. A study was carried out to produce a granular powder that can reduce the variations between products during the molding and sintering process of the powder metallurgy method. A preliminary experiment was conducted to confirm the influence of the variables in the granulation process. Through the preliminary test results, this experiment was performed with the volume of solvent of the spray drying the mixture as an independent variable, and granular powder having a mean particle size similar to that of the existing mass-production conditions and an increased apparent density was prepared. In addition, a pilot test was conducted for the molding and sintering process. The improved granular powder reduced the characteristic variation (weight variation) of the mass-produced product. 텅스텐 합금은 일반 산업분야 뿐만 아니라, 방산 분야에서도 다양하게 활용되고 있다. 방산 분야에 활용되는 일반적인 합금의 제조 방법은 주조를 통하여 제조된 합금을 단조, 압연, 압출 등의 1차 가공 후 원소재로 공급하여 제품을 생산 한다. 하지만, 텅스텐 합금은 주조 공정에 어려움이 있어 분말야금법을 활용하여 제품을 제작하고 있다. 분말야금법은 미세한 분말을 이용하여 기계적 물성과 생산성을 높일 수 있으나, 양산 단계에서 제품 간 편차를 유발할 수 있다. 미세한 분말의 장점과 제품 간 편차를 감소하기 위하여 각 장점을 갖는 과립분말 제조에 대한 연구가 필요하다. 본 연구에서는 볼밀을 이용하여 균질화를 시킨 텅스텐과 니켈, 철의 혼합분말을 용매인 순수에 투입하고 결합제인 PVA를 첨가하여 분무건조용 혼합액을 제조하였다. 혼합액을 분무건조기를 이용하여 과립분말을 제조하였고, 분말야금법의 성형 및 소결 공정 중 제품 간 편차를 줄일 수 있는 과립분말의 제조를 목표로 연구를 수행하였다. 과립 공정에서는 다양한 변수(혼합물의 농도, 결합제의 용량, 분무건조기의 건조 온도, 분무 회전 속도) 간 영향성을 확인하기 위하여 예비 실험을 실시하였다. 예비 실험 결과를 통해 분무건조용 혼합물의 용매의 용량을 독립변수로 본 실험을 수행하였고, 기존 양산 조건과 유사한 평균 입도를 가지며, 겉보기 밀도가 증가한 개선된 과립분말을 제조하였다. 추가적으로 성형 및 소결 공정에 대한 파일럿 시험을 진행하여 개선된 과립분말이 양산 제품의 특성 편차(중량 편차)를 감소하는 것을 확인하였다.

분말야금법으로 제조된 FeSi₂ 열전특성 화합물의 열처리 시간에 따른 미세조직과 상변화

박경태,신진교,홍순직,천병선,Park, Kyoung-Tae,Shin, Jin-Gyo,Hong, Soon-Jik,Chun, Byong-Sun 한국분말야금학회 2010 한국분말재료학회지 (KPMI) Vol.17 No.6

In this study, $FeSi_2$ as high temperature performance capable thermoelectric materials was manufactured by powder metallurgy.The as-casted Fe-Si alloy was annealed for homogenization below $1200^{\circ}C$ for 3 h. Due to its high brittleness, the cast alloy transformed to fine powders by ball-milling, followed by subsequent compaction (hydraulic pressure; 2 GPa) and sintering ($1200^{\circ}C$, 12 h). In order to precipitate ${\beta}-FeSi_2$, heat treatment was performed at $850^{\circ}C$ with varying dwell time (7, 15 and 55 h). As a result of this experiment thermoelectric phase ${\beta}-FeSi_2$ was quickly transformed by powder metallurgical process. There was not much change in powder factor between 7h and 55h specimens.

탈수소화 분위기가 탄탈륨 분말 수소농도에 미치는 영향 연구

이지은(Ji-eun Lee),윤진호(Jin-Ho Yoon),이찬기(Chan Gi Lee) 강원대학교 산업기술연구소 2021 産業技術硏究 Vol.41 No.1

Hydride-dehydride process for efficient recycling of tantalum (Ta) is used for manufacturer of Ta powder. In case of metal powder, Impurities as like nitride, oxygen, hydrogen is decreased of physical properties. For manufacture of Ta powder, control of theses impurities is important. In this study, to decreased of impurities on Ta powder using HDH process optimize dehydride condition. Dehydration behavior of Ta is depended on temperature, time, and atmosphere. Phase transition of Ta hydride is analyzed by X-ray diffraction (XRD). Concentration of hydrogen is decreased with temperature increased. At high temperature, concentration of hydrogen in Ta is similar according to time increased. Size and morphology of powder is not observed after dehydride. Ta powder, which is less than 20 um, concentration of hydrogen under 800 ppm is obtain.

Al-Si-SiC 복합분말과 Al-Zn-Mg계 합금분말이 혼합된 분말의 소결 거동 및 기계적 특성연구

장광주,김경태,양상선,김용진,박용호,Jang, Gwang-Joo,Kim, Kyung Tae,Yang, Sangsun,Kim, Yong-Jin,Park, Yong-Ho 한국분말야금학회 2014 한국분말재료학회지 (KPMI) Vol.21 No.6

Al-Si-SiC composite powders with intra-granular SiC particles were prepared by a gas atomization process. The composite powders were mixed with Al-Zn-Mg alloy powders as a function of weight percent. Those mixture powders were compacted with the pressure of 700 MPa and then sintered at the temperature of $565-585^{\circ}C$. T6 heat treatment was conducted to increase their mechanical properties by solid-solution precipitates. Each relative density according to the optimized sintering temperature of those powders were determined as 96% at $580^{\circ}C$ for Al-Zn-Mg powders (composition A), 97.9% at $575^{\circ}C$ for Al-Zn-Mg powders with 5 wt.% of Al-Si-SiC powders (composition B), and 98.2% at $570^{\circ}C$ for Al-Zn-Mg powders with 10 wt.% of Al-Si-SiC powders (composition C), respectively. Each hardness, tensile strength, and wear resistance test of those sintered samples was conducted. As the content of Al-Si-SiC powders increased, both hardness and tensile strength were decreased. However, wear resistance was increased by the increase of Al-Si-SiC powders. From these results, it was confirmed that Al-Si-SiC/Al-Zn-Mg composite could be highly densified by the sintering process, and thus the composite could have high wear resistance and tensile strength when the content of Al-Si-SiC composite powders were optimized.

Vacuum degassing behavior of Zr-, Ni- and Cu-based metallic glass powders

Yamasaki, Michiaki,Iwamoto, Kotaro,Tamagawa, Hirokazu,Kawamura, Yoshihito,Lee, Jin-Kyu,Kim, Hwi-Jun,Bae, Jung-Chan Elsevier 2007 Materials science & engineering. properties, micro Vol.449 No.-

<P><B>Abstract</B></P><P>The vacuum degassing behavior of Zr<SUB>55</SUB>Al<SUB>10</SUB>Ni<SUB>5</SUB>Cu<SUB>30</SUB>, Ni<SUB>59</SUB>Zr<SUB>15</SUB>Ti<SUB>13</SUB>Si<SUB>3</SUB>Sn<SUB>2</SUB>Nb<SUB>7</SUB>Al<SUB>1</SUB>, and Cu<SUB>54</SUB>Ni<SUB>6</SUB>Zr<SUB>22</SUB>Ti<SUB>18</SUB> (numbers indicate at.%) metallic glass powders has been investigated and compared with that of Al alloy powder. It was found that the alloy composition influenced the gas desorption behavior with heating <I>in vacuo</I>. Zr<SUB>55</SUB>Al<SUB>10</SUB>Ni<SUB>5</SUB>Cu<SUB>30</SUB> and Ni<SUB>59</SUB>Zr<SUB>15</SUB>Ti<SUB>13</SUB>Si<SUB>3</SUB>Sn<SUB>2</SUB>Nb<SUB>7</SUB>Al<SUB>1</SUB> metallic glass powders exhibited little H<SUB>2</SUB> gas desorption from powder surfaces during vacuum degassing. Because Zr in the Zr-based and Ni-based amorphous alloy powders produced a native zirconium oxide layer, the surface of the Zr<SUB>55</SUB>Al<SUB>10</SUB>Ni<SUB>5</SUB>Cu<SUB>30</SUB> and Ni<SUB>59</SUB>Zr<SUB>15</SUB>Ti<SUB>13</SUB>Si<SUB>3</SUB>Sn<SUB>2</SUB>Nb<SUB>7</SUB>Al<SUB>1</SUB> amorphous alloys had no influence on adsorbed H<SUB>2</SUB>O. Cu<SUB>54</SUB>Ni<SUB>6</SUB>Zr<SUB>22</SUB>Ti<SUB>18</SUB> metallic glass powder was the most affected by atmospheric H<SUB>2</SUB>O among the metallic glass powders examined in this study. The adsorbed H<SUB>2</SUB>O and Cu metal may react with each other with the formation of Cu<SUB>2</SUB>O and liberation of H<SUB>2</SUB> during vacuum degassing. In order to obtain sound P/M final products with Cu-based P/M alloys, oxygen-free copper powders should be used in well-controlled atmospheres with low H<SUB>2</SUB>O partial pressures.</P>

Microstructure and martensitic transformation characteristics of gas-atomized Ti-Ni-Cu powders

Kim, Y.w.,Choi, K.c.,Chung, Y.s.,Choi, E.,Nam, T.h. Elsevier Sequoia 2013 Journal of alloys and compounds Vol.577 No.suppl1

Three batches of Ti-Ni-Cu powders (Ti<SUB>50</SUB>Ni<SUB>45</SUB>Cu<SUB>5</SUB>, Ti<SUB>50</SUB>Ni<SUB>40</SUB>Cu<SUB>10</SUB> and Ti<SUB>50</SUB>Ni<SUB>30</SUB>Cu<SUB>20</SUB>) were prepared by gas atomization and porous specimens were fabricated by spark plasma sintering (SPS). The microstructure of as-solidified powders exhibited a cellular structure. XRD analysis showed that one-step martensitic transformation of B2-B19 occurred in all alloy powders and SPS specimens. DSC measurements of as-atomized powder, sintered bulk specimens and as-cast ingots were performed in order to study the effect of rapid solidification on martensitic transformation behaviors. The dependence of powder size on martensitic transformation temperature is very small in the rapidly solidified powders. However, the transformation temperatures were strongly dependent on the Cu-content. The martensitic transformation starting temperatures (M<SUB>s</SUB>) of Ti<SUB>50</SUB>Ni<SUB>45</SUB>Cu<SUB>5</SUB>, Ti<SUB>50</SUB>Ni<SUB>40</SUB>Cu<SUB>10</SUB> and Ti<SUB>50</SUB>Ni<SUB>30</SUB>Cu<SUB>20</SUB> powders ranging between 25 and 150μm are -4.9, -17.6 and 32.1<SUP>o</SUP>C and the austenite transformation finishing temperatures (A<SUB>f</SUB>) of Ti<SUB>50</SUB>Ni<SUB>45</SUB>Cu<SUB>5</SUB>, Ti<SUB>50</SUB>Ni<SUB>40</SUB>Cu<SUB>10</SUB> and Ti<SUB>50</SUB>Ni<SUB>30</SUB>Cu<SUB>20</SUB> powders were 15.6, -4.4 and 38.3<SUP>o</SUP>C, respectively. The M<SUB>s</SUB> and A<SUB>f</SUB> of the as-atomized powders are much smaller than those of SPS specimens and as-cast ingots for all Ti<SUB>50</SUB>Ni<SUB>45</SUB>Cu<SUB>5</SUB>, Ti<SUB>50</SUB>Ni<SUB>40</SUB>Cu<SUB>10</SUB> and Ti<SUB>50</SUB>Ni<SUB>30</SUB>Cu<SUB>20</SUB> alloy systems. The temperature hysteresis (A<SUB>f</SUB>-M<SUB>s</SUB>) of Ti<SUB>50</SUB>Ni<SUB>45</SUB>Cu<SUB>5</SUB> powders was 20<SUP>o</SUP>C and continued to decrease with increasing Cu-content. The temperature hysteresis of Ti<SUB>50</SUB>Ni<SUB>30</SUB>Cu<SUB>20</SUB> powders was only 7<SUP>o</SUP>C.

Wide-Gap Repair of Mar-M247 Superalloy via Powder Metallurgy Route

Xiufang Gong,Yankang Yu,Tianjian Wang,Ye Liu,Lin Zhang,Zhenhuan Gao,Hou Ziyong,Xu Chen,Shuang He,Xuanhui Qu 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.11

Wide-gap defects repair of Mar-M247 superalloy was investigated by utilizing powder metallurgy. New interlayer alloy withrelatively high content of B and Zr was designed based on the isothermal solidification principle. The interlayer alloy ischaracterized by relative low melting temperature (1100 °C), and the contact angle of interlayer on the Mar-M247 substrateis ~ 70º. Based on the thermodynamic calculation results, the mixture powders with 80 wt% substrate powder and 20 wt%interlayer alloy powder was used as a filler to repair the wide gap with width of 2 mm. After repaired at 1230 °C for 2 h, nearfullydense gap was obtained. MC-type carbides, MB2-type boride, M3B2-type boride and Ni5(Zr,Hf)-type intermetallic wereobserved in the liquid zone. After post-weld heat treatment, the block borides, chain carbides and eutectic are successfullyremoved, and the tensile strength of the bonding zone is close to that of the Mar-M247 superalloy.

Micro-porous Nickel Produced by Powder Metallurgy

Yamada Y.,Li Y.C.,Banno T.,Xie Z.K.,Wen C.E. 한국분말야금학회 2006 한국분말야금학회 학술대회논문집 Vol.2006 No.1

Micro-porous nickel (Ni) with an open cell structure was fabricated by powder metallurgy. The pore size of the micro-porous Ni approximated and . For comparison, porous Ni with a macro-porous structure were also prepared by both powder metallurgy (pore size ) and the traditional chemical vapour deposition method (pore size ). The mechanical properties of the micro-and macro-porous Ni samples were evaluated using compressive tests. Results indicate that the micro-porous Ni samples exhibited significantly enhanced mechanical properties, compared to those of the macro-porous Ni samples.

Influence of Mn on the Mechanical and Shape Memory Transformation Behaviours of Powder Metallurgy Processed Cu–Al–Ni SMAs

M. Muhamed Shafeeq,Hirshikesh,G. K. Gupta,D. P. Mondal 대한금속·재료학회 2024 METALS AND MATERIALS International Vol.30 No.1

In this work, a novel powder metallurgy method comprising elemental powder mixing and hot vacuum compaction wasused to produce fine-grained Cu–Al–Ni–Mn SMA successfully. The effects of Mn (0–3 wt%) addition and different Al concentrationson the mechanical and shape memory capabilities of powder-processed Cu–Al–Ni SMA were investigated. Theformation of different martensitic and secondary phases is characterized by field emission scanning electron microscope,and X-ray diffraction. The addition of Mn improved ductility and decreased phase transformation temperature of the powderprocessedSMA, which was confirmed using a three-point bending/tensile test and differential scanning calorimetry analysis.