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The Influence of Powder Size on Mechanical Properties of Small MIM Parts
Yasui Noriyuki,Satomi Hiroshi,Fujiwara Hiroshi,Ameyama Kei,Kankawa Yoshimitsu 한국분말야금학회 2006 한국분말야금학회 학술대회논문집 Vol.2006 No.1
The relationship between the powder particle size change and a mechanical property of the Metal Injection Molding (MIM) product was examined in detail. The XRD results indicate that the diffraction peaks of BCC appeared in compacts of powder particle size of 4 to as well as the bulk SUS630. However, the diffraction peaks from both BCC and FCC were observed in the compact with powder size less than . TEM observation revealed that the powder with those BCC/FCC two phase structure have a finely dispersed precipitates. Because the Si is ferrite stabilizing element, decrease of Si composition in the matrix phase by the precipitation resulted in formation of the retained austenite. Therefore, controlling the elements such as Si as well as oxygen decrease is very important to obtain a normal microstructure in ultra-fine powder (<3μm) injection molding.
Hybrid Microstructure and Mechanical Properties of HRS Processed SUS316L and Titanium Materials
Fujiwara Hiroshi,Ohta Koichi,Noro Atsushi,Ameyama Kei 한국분말야금학회 2006 한국분말야금학회 학술대회논문집 Vol.2006 No.1
SUS316L stainless steel, commercial pure Titanium and Ti-6Al-4V alloy powders applied by Mechanical Milling (MM) process are sintered by Hot Roll Sintering (HRS) process. Microstructure and mechanical properties of those HRS materials is investigated. The microstructures of materials produced by HRS process consist of fine grains and work-hardened structure, that is, the hybrid microstructure. Tensile test of the HRS material demonstrated the good mechanical properties. These results show that the HRS process is very effective to the improvement of mechanical properties in the SUS316L stainless steel, commercial pure Titanium and Ti-6Al-4V alloy.
High Temperature Deformation Behavior of Nano Grain W Produced by SPD-PM Process
Oda Eiji,Ohtaki Takao,Kuroda Akio,Fujiwara Hiroshi,Ameyama Kei,Yoshida Kayo 한국분말야금학회 2006 한국분말야금학회 학술대회논문집 Vol.2006 No.1
In this study, nano grain W is fabricated by Severe Plastic Deformation-Powder Metallurgy (SPD-PM) process. W powder and W-Re powder mixtures are processed by SPD-PM process, a Mechanical Milling (MM) process. As results, a nano grain structure, whose grain size is approximately 20nm, is obtained in W powder after MM for 360ks. A nano grain W compact, whose grain size 630nm, has excellent deformability above 1273K. A nano grain W-10Re compact is composed of equiaxed grain, a grain growth is restrained and has low dislocation density after the large deformation; therefore it is considered that W-Re compact shows superplasticity.
Application of Pseud-superplastic PM Process to Ti-Al Intermetallic Compound for MEMS Parts
Miyano Naoki,Kumagai Yusuke,Yoshimoto Masayoshi,Nishimura Yuta,Tanaka Shigeo,Ameyama Kei 한국분말야금학회 2006 한국분말야금학회 학술대회논문집 Vol.2006 No.1
A non-equilibrium powder metallurgy processing such as an MA/SPS (Mechanical Alloying / Spark Plasma Sintering) process is examined in a Ti-48moll%Al. TiAl intermetallic compound is a potential light-weight/high-temperature structural material. One of the major problems, however, limiting the practical use of the material is its poor workability. From this point, the powder metallurgy (PM) processing route has been attractive alternative of the conventional processing for such material The MA/SPS process is able to apply to a LIGA process. Optimization of the pseudo-superplasticity enables to fabricate micro-parts made of fine grained ceramics composites of TiAl by the LIGA process.
분말야금법으로 제조한 하모닉 구조재료의 신장플랜지 가공성
윤재익,이학현,박형근,김형섭,Yoon, Jae Ik,Lee, Hak Hyeon,Park, Hyung Keun,Ameyama, Kei,Kim, Hyoung Seop 한국분말야금학회 2017 한국분말재료학회지 (KPMI) Vol.24 No.2
Harmonic structure materials are materials with a core-shell structure having a shell with a small grain size and a core with a relatively large grain size. They are in the spotlight because their mechanical properties reportedly feature strength similar to that of a sintered powder with a fine grain size and elongation similar to that of a sintered powder with a coarse grain size at the same time. In this study, the tensile properties, microstructure, and stretch-flangeability of harmonic structure SUS304L made using powder metallurgy are investigated to check its suitability for automotive applications. The harmonic powders are made by mechanical milling and sintered using a spark plasma sintering method at 1173 K and a pressure of 50 MPa in a cylindrical die. The sintered powders of SUS304L having harmonic structure (harmonic SUS304L) exhibit excellent tensile properties compared with sintered powders of SUS304L having homogeneous microstructure. In addition, the harmonic SUS304L has excellent stretch-flangeability compared with commercial advanced high-strength steels (AHSSs) at a similar strength grade. Thus, the harmonic SUS304L is more suitable for automotive applications than conventional AHSSs because it exhibits both excellent tensile properties and stretch-flangeability.