Mechanical properties of (W,Ti)C and (W,Ti)C-NiAl₃ cermet consolidated by the high-frequency induction-heating method

Kim, W.,Suh, C.Y.,Roh, K.M.,Cho, S.W.,Na, K.I.,Shon, I.J. Elsevier Sequoia 2013 Journal of alloys and compounds Vol.568 No.-

In the case of cemented (W,Ti)C, Co is added as a binder for the formation of composite structures. However, the high cost of Co and the low corrosion resistance of the (W,Ti)C-Co cermet have generated interest in recent years for alternative binder phases. In this study, NiAl<SUB>3</SUB> was used as a binder and consolidated by the high-frequency induction heated sintering (HFIHS) method. The densification of both monolithic (W,Ti)C and (W,Ti)C-NiAl<SUB>3</SUB> cermet was accomplished within 3min. Highly dense (W,Ti)C and (W,Ti)C-NiAl<SUB>3</SUB> with a relative density of upto 99% were obtained within 3min by HFIHS under a pressure of 80MPa. The method was found to enable not only the rapid densification but also the prohibition of grain growth preserving the nano-scale microstructure. The average grain sizes of the sintered (W,Ti)C and (W,Ti)C-NiAl<SUB>3</SUB> were lower than 100nm. The addition of NiAl<SUB>3</SUB> to (W,Ti)C enhanced the toughness at the expense of the slight decrease in hardness. The hardness of (W,Ti)C and (W,Ti)C-NiAl<SUB>3</SUB> was significantly higher than that of (W,Ti)C-Co or (W,Ti)C-Ni. The fracture toughness and hardness values of (W,Ti)C, (W,Ti)C-5vol.%NiAl<SUB>3</SUB>, and (W,Ti)C-10vol.%NiAl<SUB>3</SUB> consolidated by HFIHS with a pressure of 80MPa and a induced current were 7.6+/-0.4MPam<SUP>½</SUP> and 2850+/-35kg/mm<SUP>2</SUP>, 8.5+/-0.3MPam<SUP>½</SUP> and 2610+/-37kg/mm<SUP>2</SUP>, 9.7+/-0.5MPam<SUP>½</SUP> and 2520+/-26kg/mm<SUP>2</SUP>, respectively.

OH (1720 MHz) MASERS: A MULTIWAVELENGTH STUDY OF THE INTERACTION BETWEEN THE W51C SUPERNOVA REMNANT AND THE W51B STAR FORMING REGION

Brogan, C. L.,Goss, W. M.,Hunter, T. R.,Richards, A. M. S.,Chandler, C. J.,Lazendic, J. S.,Koo, B.-C.,Hoffman, I. M.,Claussen, M. J. IOP Publishing 2013 The Astrophysical journal Vol.771 No.2

<P>We present a comprehensive view of the W51B H II region complex and the W51C supernova remnant (SNR) using new radio observations from the VLA, VLBA, MERLIN, JCMT, and CSO along with archival data from Spitzer, ROSAT, ASCA, and Chandra. Our VLA data include the first lambda = 400 cm (74 MHz) continuum image of W51 at high resolution (88 ''). The 400 cm image shows non-thermal emission surrounding the G49.2-0.3 H II region, and a compact source of non-thermal emission (W51B_NT) coincident with the previously-identified OH (1720 MHz) maser spots, non-thermal 21 and 90 cm emission, and a hard X-ray source. W51B_NT falls within the region of high likelihood for the position of TeV gamma-ray emission. Using the VLBA, three OH (1720 MHz) maser spots are detected in the vicinity of W51B_NT with sizes of 60-300 AU and Zeeman effect magnetic field strengths of 1.5-2.2 mG. The multiwavelength data demonstrate that the northern end of the W51B HII region complex has been partly enveloped by the advancing W51C SNR and this interaction explains the presence of W51B_NT and the OH masers. This interaction also appears in the thermal molecular gas which partially encircles W51B_NT and exhibits narrow pre-shock (Delta v similar to 5 km s(-1)) and broad post-shock (Delta v similar to 20 km s(-1)) velocity components. RADEX radiative transfer modeling of these two components yield physical conditions consistent with the passage of a non-dissociative C-type shock. Confirmation of the W51B/W51C interaction provides additional evidence in favor of this region being one of the best candidates for hadronic particle acceleration known thus far.</P>

Chlortetracycline 과 비닐포장처리에 의한 토육의 상온저장시험

이용빈,송계원,고준수 한국축산학회 1965 한국축산학회지 Vol.7 No.1

The shelf-life of cony meat was studied out in this experiment. After the rabbit dressed out, the meat was treated with 10 p.p.m. Chlortetracycline (C.T.C.) solution and packed with polyethylene. The samples were taken from the muscle of the rump and the round. We allotted eight treatments: That is, two temperature levels (5℃ and 20℃) that have two treatments: Control and C.T.C.-Treated. And each treatment of each temperature levels has two treatments, Control and Packed with Polyethylene. The items investigated are the change of the number of microorganisms, pH, and methylene blue reducing time. The results are as follows: 1. Effectively, C.T.C. suppressed the increasing of microorganisms of cony meat during the storage. And there was highly significant difference at 1.0% level in the C.T.C.-Treated meats on the Ist day of storage. The number of microorganism reached 10^8 per gram in 20℃-Control by the 2nd day of storage and 10^8 per gram by the 7th day of storage. 2. The increasing of yeasts was apparent in 20℃-C.T.C.-Treated on the 5th and 6th day of storage. And on the 7th day of storage, molds were also found. 3. Polyethylene packing was effective (significant at 5.0%) on the 2nd, 3rd, 4th, and 5th day of storage in 5℃-Control, and on the 2nd, 3rd day of storage in 20℃-C.T.C.-Treated. 4. The pH of cony meat during storage was lower in 20℃-C.T.C.-Treated by the 4th day of storage than in 5℃-Control, but after 5th day of storage, the pH of meat. was increased rapidly. 5. The C.T.C. treatment has a more strong effect upon the change of pH of cony meat than the polyethylene packing throughout the storage. And the effect of the temperature was greater than that of C.T.C.-Treatment. 6. C.T.C.-Treatment has shorten methylene blue reducing time than control (significant at 1.0%). And the methylene blue reducing time of 20℃-C.T.C.-Treated was similart to that of 5℃-Control all throughout the experiment period. 7. Polyethylene packing has an effect upon the methylene blue reducing time on the 3rd, 4th day of storage (significant at 5.0%). In the testing of L.S.D., there was no significant differences throughout the period.

한우 비육에 관한 연구 1 . Methylthiouracil 첨가 및 Estradiol 17β - Cypionate 주사가 약령 모우 비육에 미치는 효과

김창기 ( C K Kim ),이택원 ( T W Lee ),김종욱 ( J W Kim ),배대식 ( D S Bae ),오선균 ( S K Oh ),조지훈 ( C H Cho ),김법회 ( B H Kim ),김상렬 ( S Y Kim ),배신석 ( S S Bae ) 한국축산학회 1971 한국축산학회지 Vol.13 No.1

This study was performed to affirm any effects of methylthiouracil and estradiol 17β-cypionate administered to young bulls for short term fattening. Eighteen bulls of Korean native breed, approximately 1.5 to 2 years of age and 260㎏ to 360㎏ in weight, were used in this study. All bulls had received a basal ration of soiling corn and concentrate made up of 55% grains, 40% brans and 5% others, in a period of 40 days. Bulls were divided into six groups as follows: group C was not treated, group M-2 received 2g of methylthiouracil per day, group M-3 received 3g of methylthiouracil per day, group EM-0 was injected intramusculary with 25㎎ of estradiol 17β-cypionate in the neck region 10 days after the beginning of the fattening period, group EM-2 was injected with estradiol 17β-cypionate as above mentioned and simultaneously received 2g of methylthiouracil per day, and group EM-3 was injected with estradiol 17β-cypionate as above mentioned and simultaneously received 3g of methylthiouracil per day. The results obtained were summarized as follows. 1. The average daily gain was for group C: 0.83㎏, group M-2: 1.07㎏, group M-3: 1.40㎏, group EM-0, 0.93㎏, group EM-2: 0.95㎏, and group EM-3: 1.18㎏. The M-3 group gained significantly(P$lt;0.05) more weight than C and EM-0 group. There were no significant differences in the average daily gain between the groups injected with estradiol 17β-eypionate and the control group. 2. The average daily concentrate intake was as follows: group C: 5.47㎏, group M-2: 5.00㎏, group M-3: 4.52㎏, group EM-0: 5.21㎏, group EM-2: 4.35㎏, and group EM-3: 4.61㎏. The consumption of concentrate was decreased by 17% in the M-3 group compared with the C group. There was no significant difference in the soiling corn intake among these groups. 3. Feed consumed for 1㎏ gain were decreased by the supplementation of methylthiouracil. The consumption of DCP for 1㎏ gain was in group C: 0.82㎏, group M-2: 0.59㎏, group M-3: 0.41㎏, group EM-0: 0.70㎏, group EM-2: 0.59㎏, and group EM-3: 0.50㎏. The amounts of TDN required were; group C: 6.57㎏, group M-2: 4.76㎏, group M-3: 3.39㎏, group EM-0: 5.67㎏, group EM-Z: 4.87㎏, and group EM-3: 4.08㎏. The consumption of DCP and TDN for 1㎏ gain in the M-3 group was about a half of that in the C group. 4. There was not any significant difference in the increase in body measurements among the various groups. 5. The average margins in the fattening period of 40 days were for group C: 2,950won, group M-2: 5,327won, group M-3: 9,158won, group EM-0: 3,310won, group EM-2: 3,623won, and group EM-3: 5,575won. The margin of group M-3 was about three times higher than that of group C. In short, this experiment demonstrated that methylthiouracil when fed to young native Korean bulls at the proper level 40 days before slaughter would bring a noticeable effect on weight gain, feed efficiency and economic advantage. There were no advantages from the simultaneous injecting estradiol 17β-cypionate with methylthiouracil. The proper supplementation level of methylthiouracil would appear to be 3g per head per day in this experiment.

소 c-KIT Receptor 유전자의 다형성에 관한 연구

장요순,김태헌,윤두학,박응우,이혜원,이학교,정일정 한국동물자원과학회 2002 한국축산학회지 Vol.44 No.6

소의 흰 반점 관련 후보유전자로 c-KIT receptor 유전자를 선정하여, c-KIT receptor 유전자내의 변이를 탐색하고 변이가 흰반점 표현형과 연관성이 있는지를 분석하였다. 한우, Angus, Brown Swiss, Charolais, Hereford, Holstein, Limousin 및 Simmental 등 8개 품종의 DNA 시료를 사용하여 c-KIT receptor 유전자의 intron 6번 영역에서 다형성을 조사하고 분석하였다. c-KIT receptor 유전자의 intron 6번 영역에서는 4개의 염기치환이 발견되어, MspⅠ, BsrBⅠ 및 NdeⅠ 제한효소를 이용하여 PCR-RFLP 분석을 실시하였다. Intron 6번을 포함하는 영역의 PCR 산물 크기는 2,440 bp 이었다. MspⅠ다형성은 PCR-RFLP 분석 결과 3개의 대립유전자가 존재하였으며, 한우품종에서는 3개의 대립유전자 모두가 발견되었고, CC 형태이 유전자형을 제외한 5개의 유전자형 (AA, AB, AC, BC 및 BB)을 확인하였다. Angus, Brown Swiss, Hereford, Holstein 및 Simmental 품종에서는 A 대립유전자만을 갖는 것으로 조사되었고, 한우는 44%만 AA 유전자형을 나타내었다. BsrBⅠ 다형성은 2개의 대립유전자로서 3개의 유전자형이 나타나는 것을 확인하였으며, Charolais 및 Hereford 품종이 다른 소 품종에 비하여 A 대립유전자의 빈도가 높게 나타났다. NdeⅠ 다형성을 분석한 결과 Brown Swiss 품종에서는 NdeⅠ에 의해 절단되는 형태인 A 대립유전자만 관찰되었으며, Holstein 품종은 92%, Simmental 품종은 72%가 절단되는 형태를 나타내어, 모색이 흰색을 띠는 소 품종에서 절단되는 형태가 많았다. 소 c-KIT receptor 유전자의 intron 6번 영역에서 확인된 4개의 염기치환은 품종에 따라 다른 빈도를 보였으나, 이들 염기치환과 흰 반점과의 연관성에 대한 증거는 발견하지 못하였다. 그러므로 소의 흰 반점과 c-KIT receptor 유전자 내의 변이와의 관련성은 다른 영역에 대한 추가적인 분석과, 이미 보고된 다른 모색관련 유전자의 다형성과의 연관성 분석 등과 같은 연구가 필요한 것으로 판단된다. We considered KIT gene as a candidate gene for the white-spotting pattern in cattle. This study was carried out to detect genetic variation of c-KIT receptor gene and to investigate association between the mutation and the white-spotting pattern in cattle. PCR-RFLP analysis within intron 6 of c-KIT receptor gene were performed with 8 cattle breeds including Hanwoo, Angus, Brown Swiss, Charolais, Hereford, Holstein, Limousin and Simmental. When PCR product of approximately 2,440 bp including intron 6 of c-KIT receptor gene was sequenced, four nucleotide substitutions were found within intron 6 of the bovine c-KIT receptor gene. In PCR-RFLP analysis, three alleles (A, B and C), two alleles (A and B) and two alleles (A and B) at each locus were identified by Msp Ⅰ, BsrBⅠ and NdeⅠ, respectively. Although frequencies of allele at each locus were different among cattle breeds, we could not get any evidence related with white or white spotting phenotypes in these mutations on intron 6 of c-KIT receptor gene. However, we can not entirely exclude the possibility that c-KIT receptor gene is responsible for white spotting phenotype in cattle. Thus, further studies need to detect other mutations in c-KIT receptor gene and to test association of those mutations and coat color phenotypes in cattle.

Chemical inhibitors of c-Met receptor tyrosine kinase stimulate osteoblast differentiation and bone regeneration

Kim, J.W.,Lee, M.N.,Jeong, B.C.,Oh, S.H.,Kook, M.S.,Koh, J.T. North-Holland 2017 European journal of pharmacology Vol.806 No.-

<P>The c-Met receptor tyrosine kinase and its ligand, hepatocyte growth factor (HGF), have been recently introduced to negatively regulate bone morphogenetic protein (BMP)-induced osteogenesis. However, the effect of chemical inhibitors of c-Met receptor on osteoblast differentiation process has not been examined, especially the applicability of c-Met chemical inhibitors on in vivo bone regeneration. In this study, we demonstrated that chemical inhibitors of c-Met receptor tyrosine kinase, SYN1143 and SGX523, could potentiate the differentiation of precursor cells to osteoblasts and stimulate regeneration in calvarial bone defects of mice. Treatment with SYN1143 or SGX523 inhibited HGF-induced c-Met phosphorylation in MC3T3-E1 and C3H10T1/2 cells. Cell proliferation of MC3T3-E1 or C3H10T1/2 was not significantly affected by the concentrations of these inhibitors. Co-treatment with chemical inhibitor of c-Met and osteogenic inducing media enhanced osteoblast-specific genes expression and calcium nodule formation accompanied by increased Runx2 expression via c-Met receptor-dependent but Erk-Smad signaling independent pathway. Notably, the administration of these c-Met inhibitors significantly repaired critical-sized calvarial bone defects. Collectively, our results suggest that chemical inhibitors of c-Met receptor tyrosine kinase might be used as novel therapeutics to induce bone regeneration.</P>

Fabrication of ex situ processed MgB₂ wires using nano carbon doped powder

Lee, C.M.,Park, J.H.,Hwang, S.M.,Lim, J.H.,Joo, J.,Kang, W.N.,Kim, C.J. North-Holland 2009 Physica. C, Superconductivity Vol.469 No.15

We fabricated ex situ MgB<SUB>2</SUB> wires using C-doped MgB<SUB>2</SUB> powder as a precursor in order to improve the core density of the wires and their C doping content. The C-doped powder was prepared with Mg, B, and nano carbon (NC) powders by the in situ technique and then MgB<SUB>2-x</SUB>C<SUB>x</SUB> (x=0, 0.01, and 0.03) wires were fabricated by the ex situ technique using the powder-in-tube method. The phase formation, lattice change, and microstructure were characterized and correlated with the T<SUB>c</SUB> and J<SUB>c</SUB> variations. We observed that the ex situ wire had a higher core density than the in situ wire, however its morphology consisted of agglomerated particles, indicating that sintering and grain growth did not occur completely, even though the sintering was conducted at high temperature (1000<SUP>o</SUP>C). As the C content increased, T<SUB>c</SUB> decreased, while the decrease of J<SUB>c</SUB> with increasing magnetic field became smaller. The J<SUB>c</SUB> of MgB<SUB>1.97</SUB>C<SUB>0.03</SUB> wire made by the ex situ technique was 3.34kA/cm<SUP>2</SUP> at 6.6T and 5K which is comparable to that of the in situ wire (4.81kA/cm<SUP>2</SUP> at 6.6T and 5K).

주성분 분석을 이용한 거세한우의 체형분류에 관한 연구

하동우,김현철,김병우,이문연,이종헌,신철교,도창희,이정규 한국동물자원과학회 2002 한국축산학회지 Vol.44 No.6

1997년부터 2001년까지 (사)한국종축개량협회의 전국한우능력평가대회에 출품된 642두의 거세한우의 도축 전까지 4회에 걸쳐 주요 10개 부위의 체형 측정치를 조사하여 주성분 분석을 이용하여 체형을 분류하였으며, 각 체형 측정치의 주성분 지수와 도체 형질과의 상관관계를 분석하였으며, 그 결과를 요약하면 다음과 같다. 1. 1차, 2차, 3차 및 4차 체형 측정치의 principal component(이하 P.C) 1의 분산은 각각 7.610, 8.297, 7.269 및 5.736로서 전체분산 중 76.0%, 83.0%, 72.7% 및 57.4%를 나타낼 수 있었고, P.C 1, P.C 2, P.C 3의 합은 전체분산 중 각각 86.69%, 90.49%, 84.62% 및 77.26%를 나타났다. 2. 각 차수별 체형 측정치의 P.C 1의 모든 계수가 양(+)이어서 일반적으로 좋은 체구의 크기를 나타내었으며, 체구의 크기에 가장 크게 영향을 미치는 형질은 흉심(0.328∼0.339)과 요각폭(0.325∼0.341)이였다. 또한 P.C 2, P.C 3 및 P.C 4는 각 차수별로 다양하게 나타났다. 3. 1차, 2차, 3차 및 4차 체형 측정치의 주성분 지수들과 도체형질간의 상관계수 추정에서 대부분의 분산을 차지하는 P.C 1은 도체중(0.539∼0.755), 일당증체량(0.256∼0.564), 등지방두께(0.227∼0.280) 및 배최장근단면적(0.187∼0.344)간에 정(+)의 상관을 보였으며, 육량지수(-0.246∼-0.110)와는 부(-)의 상관을 보였고, 근내지방도(0.066∼0.099)와는 대부분 유의적인 상관을 보이지 않거나 낮은 상관을 보였고, P.C 2, P.C 3 및 P.C 4는 주성분 지수들의 값에 따라 도체형질과 다양한 상관관계를 보였다. 단일 체형형질과 도체형질간의 상관 그리고 P.C 1의 주성분 지수와 도체형질과의 상관간에는 큰 차이가 없었다. Data were consisted of the ten body measurements (withers height, rump height, body length, chest depth, chest width, rump width, rump length, thurls width, hipbone width and chest girth) of 642 steers (Korean cattle), which was entered in the National Beef Quality Contest hosted by the Korea Animal Improvement Association from 1997 to 2001. A principal components analysis was used to classify the body types of the steers, and estimate the correlations between carcass traits and principal components for the body measurements of the first, second, third and fourth period, respectively. The first principal component of body measurements at the first, second, third and fourth period accounted for 76.0%, 83.0%, 72.7% and 57.4% of the total variance, respectively. The sum of first, second and third principal component at each period accounted for 86.69%, 90.49%, 84.62% and 77.26% of the total variance, respectively. At each period, all the first principal component of the body measurements were positive and it generally showed large framed body shape. The size of body was influenced mostly by chest depth(0.328∼0.339) and rump length(0.325∼0.341). The second, third and fourth principal component at the each period were various. There were positive correlations between principal components index of each period and carcass traits such as carcass weight(0.539∼0.755), average daily gain(0.256∼0.564), backfat thickness(0.227∼0.280), and eye muscle area(0.187∼0.344). The correlation with yield grade index(-0.246∼-0.110), however, was negative. The correlation with marbling score(0.066∼0.099) was low or statistically insignificant. According to principal component indexes of the second, third, and fourth components, the correlations with the carcass traits were various. There were no large differences between the correlations of the single body measurement trait with the carcass traits and the correlations of the first principal component indexes with the carcass traits.

터키種 잎담배 生産에 關한 硏究

盧載榮,鄭元采,安長憲,卞珠燮,姜信寓 충북대학교 엽연초연구소 1974 煙草硏究 Vol.2 No.-

I.Influence of deficient or excessive supply of soil moisture. The variety used in this study were Turkish varieties (Smyrna, Samsun, Zichna and Xanthi). Soil moisture content were 30%, 45% and 60% to maximum water-holding capacity for whole growth period. This experiment was carried out to study on the influence of soil moisture to growth and physiology of Turkish varieties. The results are summarized as follow ; a. Dry weight of Samsun and Zichna were-increased at 45% soil moisture content, but Smyrna and Xanthi at 60%. In every soil moisture treatmennt, there were significant difference between D plot and M, W plot but there were no significant difference between M plot and W plot. b. Percentage of dry matter of Smyrna was higher then those of the other varieties in the D plot and W plot. c. Leaf area was increased ill the Samsun of which process was slightly late. In every soil moisture treatment, M plot and W plot were higher than D plot. d. Dry weight per unit leaf area of Smyrna and Zichna were higher than that of Xanthi and Samsun. e. Percentage of dried up leaves was the W plot, and lower at the D and M plot. Smyrna was lower at M plot, Zichna at D and M plot, Xanthi at D plot, but Samsun was no difference among plots. f. In the number of harvested leaves, Smyrna was increased in order W>M>D. In the number of harvested leaves, Smyrna showed difference according to the soil moisture in order W>M>D plot, but Samsun and Zichna showed no difference among each treatments, Xanthi was higher in M plot than D and W plot. From those results, Smyrna showed the highest dry weight on account of the weight of leaf area and percentage of dry weight increased, it was decreased in order Zichna>Samsun Xanthi in the each soil moisture contents. Number of harvested leaves, dried up leaves, leaf area and number of harvested leaves but decreased, percentage of dry matter W treatment increased the number of total leaves, number of dried up leaves, leaf area, percentage of dried up leaves and percentage of dry matter. Yields were the lowest at D treated, there were no difference between M and W treatment. II.Influence of deficient or excessive supply of soil moisture at different growing stages. This experiment was carried out to study on the influence to the growth and physiology according to the soil moisture content during each growth stage on Turkish varieties culture. The varieties used in this study were Samsun, Zichna and Xanthi. The results are summarized as follow; a. Dry leaf weight was decreased in order Zichna>Samsun>Xanthi, there were remakable difference among every variety. In each soil moisture content, weight of dry matter was increased by M and W treated at late stage after MW and MM treated at early and middle stage of growth DWM and MDM plot. Dry leaf weight was decreased at D plot more than M and W plot late stage after early stage was treated by MW and MM. Dry leaf weight was the highest at WWM treate, dthere were high significant difference between varieties and soil moisture contents. b. Percentage of dry matter was decreased in order Zichna=Xanthi>Samsun. In soil moisture treated, it was increased in D treated at the latter stage after MM, MW and WM treated at early and middle stage, but it was decreased by DDM, DWD, MDM, WWD, WMM, and WWM treated. There were high significant interaction between varieties and soil moisture contents. c. Leaf area showed in order Samsun=Zichna>Xanthi. In soil moisture treated, leaf area was increased by WM, MM and MW treated at the middle and latter stage after D treated at early stage, but it was decreased at WWD, WMD, WWM, MWD and MMD treated. d. Dry weight per unit leaf area were no difference among varieties, in soil moisture treated, it was increased by the MMW, MWD, MMD, WMD and DMW treated, weight of per unit leaf area showed significant difference interaction between varieties and soil moisture contents. d. Percentage of dried up leaves showed as follow, Samsun>Xanthi, Samsun=Zichna, Zihna=Xanthi. In soil moisture treated, it was increased by M and W treated at early stage than D treated. f. Number of harvested leaves was decreased in order Xanthi>Samsun>Zichna, there were no difference among soil moisture contents, but appeard high significant difference at the interaction between varieties and soil moisture contents. As the results of this experiment, especially, this experiment will be continue on the influence of soil moisture condition in order to development of home production system.

The high thermal stability induced by a synergistic effect of ZrC nanoparticles and Re solution in W matrix in hot rolled tungsten alloy

Zhang T.,Du W.Y.,Zhan C.Y.,Wang M.M.,Deng H.W.,Xie Z.M.,Li H. 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.8

The synergistic effect of ZrC nanoparticle pining and Re solution in W matrix on the thermal stability of tungsten was studied by investigating the evolution of the microstructure, hardness and tensile properties after annealing in a temperature range of 1000e1700 C. The results of metallography, electron backscatter diffraction pattern and Vickers micro-hardness indicate that the rolled W-1wt%Re-0.5 wt% ZrC alloy has a higher recrystallization temperature (1600 Ce1700 C) than that of the rolled pure W (1200 C), W-0.5 wt%ZrC (1300 C), W-0.5 wt%HfC (1400e1500 C) and WeK-3wt%Re alloy fabricated by the same technology. The molecular dynamics simulation results indicated that solution Re atoms in W matrix can slow down the self-diffusion of W atoms and form dragging effect to delay the growth of W grain, moreover, the diffusion coefficient decrease with increasing Re content. In addition, the ZrC nanoparticles can pin the grain boundaries and dislocations effectively, preventing the recrystallization. Therefore, synergistic effect of solid solution Re element and dispersed ZrC nanoparticles significantly increase recrystallization temperature