Hōʻike nā mea hoʻohui HEA i hoʻoikaika ʻia i kahi hui maikaʻi loa o nā waiwai mechanical.

ʻO CoCrFeNi kahi mea hoʻohuihui kiʻekiʻe entropy kiʻekiʻe (HEA) i aʻo maikaʻi ʻia me ka ductility akā palena ʻia ka ikaika. ʻO ka manaʻo o kēia haʻawina ʻo ia ka hoʻomaikaʻi ʻana i ke koena o ka ikaika a me ka ductility o ia mau HEA ma o ka hoʻohui ʻana i nā nui like ʻole o SiC me ka hoʻohana ʻana i ke ʻano hoʻoheheʻe arc. Ua hoʻokumu ʻia ʻo ka hiki ʻana o ka chromium i ke kumu HEA ke kumu o ka decomposition o SiC i ka wā heheʻe. No laila, ʻo ka hui ʻana o ke kalapona manuahi me ka chromium e alakaʻi i ka hoʻokumu ʻia ʻana o ka chromium carbide i loko, ʻoiai e mau ana ke silikona manuahi i ka hoʻonā i ke kumu HEA a / a i ʻole e launa pū me nā mea e hoʻokumu i ke kumu HEA e hana i nā silicides. Ke piʻi aʻe ka maʻiʻo SiC, hoʻololi ka māhele microstructure i kēia kaʻina: fcc → fcc + eutectic → fcc + chromium carbide flakes → fcc + chromium carbide flakes + silicide → fcc + chromium carbide flakes + silicide + graphite balls / graphite flakes. Hōʻike nā composites i kahi ākea loa o nā waiwai mechanical (ikaika hua mai ka 277 MPa ma luna o 60% elongation a hiki i 2522 MPa ma 6% elongation) i hoʻohālikelike ʻia me nā alloys maʻamau a me nā alloys entropy kiʻekiʻe. ʻO kekahi o nā composites entropy kiʻekiʻe i hoʻomohala ʻia e hōʻike ana i kahi hui maikaʻi loa o nā waiwai mechanical (ikaika hua 1200 MPa, elongation 37%) a noho i nā ʻāpana i hiki ʻole ke loaʻa ma mua ma ke kiʻi hoʻoulu ʻana i ka stress-elongation. Ma waho aʻe o ka elongation kupaianaha, ʻo ka paʻakikī a me ka ikaika o ka hoʻoulu ʻana o HEA composites i ka laulā like me nā aniani metala nui. No laila, ua manaʻo ʻia ʻo ka hoʻomohala ʻana i nā composites kiʻekiʻe-entropy hiki ke kōkua i ka hoʻokō ʻana i kahi hui maikaʻi loa o nā waiwai mechanical no nā noi hoʻolālā holomua.
ʻO ka hoʻomohala ʻana i nā ʻāpana entropy kiʻekiʻe he manaʻo hou i ka metallurgy1,2. Ua hōʻike ʻia nā ʻāpana entropy kiʻekiʻe (HEA) i kekahi mau hihia i kahi hui maikaʻi loa o ke kino a me nā waiwai mechanical, e komo pū me ke kūpaʻa wela kiʻekiʻe3,4 superplastic elongation5,6 kūpaʻa luhi7,8 kūpaʻa corrosion9,10,11, kūʻē maikaʻi loa i ka lole12,13,14 ,15 a me na waiwai tribological15 ,16,17 a hiki i ke kiʻekiʻe wela18,19,20,21,22 a me ka mechanical waiwai ma haʻahaʻa. mahana23,24,25. ʻO ka hui maikaʻi ʻana o nā waiwai mechanical i loko o ka HEA e pili ana i nā hopena nui ʻehā, ʻo ia hoʻi ka entropy hoʻonohonoho kiʻekiʻe26, distortion lattice ikaika27, diffusion lohi28 a me ka hopena cocktail29. Hoʻokaʻawale ʻia nā HEA e like me nā ʻano FCC, BCC a me HCP. Loaʻa i ka FCC HEA nā mea hoʻololi e like me Co, Cr, Fe, Ni a me Mn a hōʻike i ka ductility maikaʻi loa (ʻoiai ma ka wela haʻahaʻa25) akā haʻahaʻa ka ikaika. Hoʻokumu pinepine ʻia ʻo BCC HEA me nā mea hoʻonaninani kiʻekiʻe e like me W, Mo, Nb, Ta, Ti a me V a he ikaika kiʻekiʻe loa akā he haʻahaʻa haʻahaʻa a me ka ikaika kikoʻī haʻahaʻa30.
Ua noiʻi ʻia ka hoʻololi microstructural o HEA e pili ana i ka mīkini, ka hana thermomechanical a me ka hoʻohui ʻana o nā mea e loaʻa ai ka hui maikaʻi loa o nā waiwai mechanical. Hoʻopili ʻia ʻo CoCrFeMnNi FCC HEA i ka deformation plastic koʻikoʻi e ka torsion kiʻekiʻe, e alakaʻi ana i ka piʻi nui ʻana o ka paʻakikī (520 HV) a me ka ikaika (1950 MPa), akā ʻo ka hoʻomohala ʻana i kahi microstructure nanocrystalline (~ 50 nm) hana i ka alloy brittle31 . Ua ʻike ʻia ʻo ka hoʻohui ʻana o ka twinning ductility (TWIP) a me ka transformation induced plasticity (TRIP) i loko o CoCrFeMnNi HEAs e hāʻawi i ka hardenability hana maikaʻi e hopena ai i ka tensile tensile kiʻekiʻe, ʻoiai ma ka lilo o nā waiwai ikaika tensile maoli. Ma lalo (1124 MPa) 32. ʻO ka hoʻokumu ʻana i kahi microstructure layered (ʻo ia kahi ʻāpana lahilahi deformed a me kahi kumu ʻole) i loko o ka CoCrFeMnNi HEA me ka hoʻohana ʻana i ka pana pana i hopena i ka piʻi ʻana o ka ikaika, akā ua kaupalena ʻia kēia hoʻomaikaʻi ʻana ma kahi o 700 MPa33. I ka ʻimi ʻana i nā mea me ka hui maikaʻi loa o ka ikaika a me ka ductility, ua noiʻi ʻia ka hoʻomohala ʻana o nā HEA multiphase a me nā HEA eutectic me ka hoʻohana ʻana i nā mea hoʻohui o nā mea non-isoatomic34,35,36,37,38,39,40,41. ʻOiaʻiʻo, ua ʻike ʻia he ʻoi aku ka maikaʻi o ka puʻunaue ʻana o nā ʻāpana paʻakikī a palupalu i nā alloys high-entropy eutectic hiki ke alakaʻi i kahi hui maikaʻi o ka ikaika a me ka ductility35,38,42,43.
ʻO ka ʻōnaehana CoCrFeNi kahi i aʻo nui ʻia ʻo FCC high-entropy alloy. Hōʻike kēia ʻōnaehana i nā waiwai paʻakikī o ka hana44 a me ka ductility maikaʻi loa45,46 ma nā wela haʻahaʻa a kiʻekiʻe. Ua hana ʻia nā hoʻāʻo like ʻole e hoʻomaikaʻi i kona ikaika haʻahaʻa haʻahaʻa (~ 300 MPa)47,48 me ka hoʻomaʻemaʻe palaoa25, heterogeneous microstructure49, precipitation50,51,52 a me transformation-induced plasticity (TRIP)53. ʻO ka hoʻomaʻemaʻe ʻana i ka palaoa o ka hoʻolei ʻana i ke alo cubic HEA CoCrFeNi ma ke kiʻi anuanu ma lalo o nā kūlana koʻikoʻi e hoʻonui i ka ikaika mai kahi o 300 MPa47.48 a i 1.2 GPa25, akā hoʻemi i ka nalowale o ka ductility mai ka 60% a hiki i ka 12.6%. ʻO ka hoʻohui ʻana o Al i ka HEA o CoCrFeNi i hoʻokumu ʻia i kahi microstructure heterogeneous, i hoʻonui i kona ikaika hua i 786 MPa a me kona elongation pili ma kahi o 22%49. Ua hoʻohui pū ʻia ʻo CoCrFeNi HEA me Ti a me Al e hoʻokumu i ka ua, a laila e hoʻoikaika ana i ka ua, e hoʻonui ana i kona ikaika hua i 645 MPa a me ka elongation i 39%51. Ua hoʻonui ka TRIP mechanical i ka 841 MPa a me ka elongation i ka 76%53.
Ua hoʻāʻo pū ʻia e hoʻohui i ka hoʻoikaika ceramic i ka HEA face centered cubic matrix e hoʻomohala i nā composites entropy kiʻekiʻe e hiki ke hōʻike i kahi hui maikaʻi o ka ikaika a me ka ductility. ʻO nā mea hui me ka entropy kiʻekiʻe ua hana ʻia e ka hoʻoheheʻe ʻana i ka vacuum arc44, mechanical alloying45,46,47,48,52,53, spark plasma sintering46,51,52, vacuum hot pressing45, hot isostatic pressing47,48 a me ka hoʻomohala ʻana i nā kaʻina hana additive43, 50. Ua hoʻohana ʻia nā Carbides, oxides a me nā nitrides e like me WC44, 45, 46, Al2O347, SiC48, TiC43, 49, TiN50 a me Y2O351 e like me ka ceramic reinforcement i ka hoʻomohala ʻana i nā composites HEA. He mea koʻikoʻi ke koho ʻana i ka matrix HEA kūpono a me ka ceramic i ka hoʻolālā ʻana a me ka hoʻomohala ʻana i kahi hui HEA ikaika a paʻa. Ma kēia hana, ua koho ʻia ʻo CoCrFeNi i mea matrix. Ua hoʻohui ʻia nā ʻano nui o SiC i ka CoCrFeNi HEA a ua aʻo ʻia ko lākou hopena i ka microstructure, haku mele, a me nā waiwai mechanical.
ʻO nā metala hoʻomaʻemaʻe kiʻekiʻe ʻo Co, Cr, Fe, a me Ni (99.95 wt%) a me ka pauka SiC (ka maʻemaʻe 99%, ka nui -400 mesh) ma ke ʻano o nā ʻāpana haʻahaʻa i hoʻohana ʻia e like me nā mea maka no ka hana ʻana i nā composites HEA. Ua hoʻokomo muaʻia ka hui isoatomic o ka CoCrFeNi HEA i loko o ka hemispherical wai-cooled copper mold, a laila ua hoʻokuʻuʻia ke keʻena i 3·10-5 mbar. Hoʻokomo ʻia ke kinoea argon maʻemaʻe kiʻekiʻe no ka hoʻokō ʻana i ka vacuum i koi ʻia no ka hoʻoheheʻe ʻana me ka tungsten electrodes non-consumable. Hoʻohuli ʻia nā ingots hopena a hoʻoheheʻe ʻia ʻelima mau manawa e hōʻoia i ka homogeneity maikaʻi. Ua hoʻomākaukau ʻia nā composites high-entropy o nā mele like ʻole ma o ka hoʻohui ʻana i kekahi nui o SiC i nā pihi equiatomic CoCrFeNi i loaʻa, i hoʻohui hou ʻia e ka hoʻohuli ʻana ʻelima a me ka hoʻoheheʻe ʻana i kēlā me kēia hihia. Ua ʻoki ʻia ke pihi hoʻoheheʻe ʻia mai ka composite i loaʻa me ka hoʻohana ʻana iā EDM no ka hoʻāʻo hou ʻana a me ke ʻano. Ua hoʻomākaukau ʻia nā laʻana no nā haʻawina microstructural e like me nā ʻano metallographic maʻamau. ʻO ka mea mua, ua nānā ʻia nā laʻana me ka microscope māmā (Leica Microscope DM6M) me ka polokalamu Leica Image Analysis (LAS Phase Expert) no ka nānā ʻana i ka pae quantitative. ʻEkolu kiʻi i lawe ʻia ma nā wahi like ʻole me ka nui o kahi o 27,000 µm2 i koho ʻia no ka nānā ʻana. ʻO nā haʻawina microstructural kikoʻī hou aʻe, me ka nānā ʻana i ka haku mele a me ka nānā ʻana i ka māhele ʻana, ua hana ʻia ma kahi microscope electron scanning (JEOL JSM-6490LA) i lako me kahi ʻōnaehana hoʻoheheʻe ikehu (EDS). Ua hana ʻia ke ʻano o ke ʻano aniani o ka hui HEA me ka hoʻohana ʻana i kahi ʻōnaehana diffraction X-ray (Bruker D2 phase shifter) me ka hoʻohana ʻana i kahi kumu CuKα me ka nui o ka pae o 0.04 °. Ua aʻo ʻia ka hopena o nā hoʻololi microstructural i nā waiwai mechanical o HEA composites me ka hoʻohana ʻana i nā hoʻokolohua microhardness Vickers a me nā hoʻāʻo hoʻoemi. No ka ho'āʻo paʻakikī, hoʻohana ʻia kahi haʻawe o 500 N no 15 mau kekona me ka hoʻohana ʻana i 10 mau indentations i kēlā me kēia specimen. Ua hoʻokō ʻia nā hoʻokolohua hoʻopaʻa ʻana o HEA composites ma ka lumi wela ma nā ʻāpana ʻāpana ʻehā (7 mm × 3 mm × 3 mm) ma kahi mīkini hoʻāʻo honua Shimadzu 50KN (UTM) ma ka helu kānana mua o 0.001/s.
Ua hoʻomākaukau ʻia nā composites entropy kiʻekiʻe, i kapa ʻia ma hope mai he mau laʻana S-1 a i S-6, ma ka hoʻohui ʻana i 3%, 6%, 9%, 12%, 15%, a me 17% SiC (nā mea a pau ma ke kaumaha%) i kahi matrix CoCrFeNi . pakahi. ʻO ka laʻana kuhikuhi i hoʻohui ʻole ʻia ʻo SiC ma kēia hope aku i kapa ʻia ʻo ia ka laʻana S-0. Hōʻike ʻia nā micrographs optical o nā composites HEA i kūkulu ʻia ma Fig. 1, kahi, ma muli o ka hoʻohui ʻana o nā mea hoʻohui like ʻole, ua hoʻololi ʻia ka microstructure hoʻokahi-phase o ka CoCrFeNi HEA i microstructure i loaʻa i nā pae he nui me nā ʻano morphology, nui, a me ka hāʻawi ʻana. Ka nui o SiC i ka haku mele. Ua hoʻoholo ʻia ka nui o kēlā me kēia māhele mai ka nānā ʻana i nā kiʻi me ka hoʻohana ʻana i ka polokalamu LAS Phase Expert. Hōʻike ka hoʻokomo ʻana i ke Kiʻi 1 (luna ʻākau) i kahi laʻana no kēia loiloi, a me ka hakina ʻāpana no kēlā me kēia māhele māhele.
ʻO nā micrographs oki o ka haku mele-entropy kiʻekiʻe: (a) C-1, (b) C-2, (c) C-3, (d) C-4, (e) C-5 a me (f) C- 6. Hōʻike ka mea hoʻokomo i kahi laʻana o nā hopena hoʻohālikelike kiʻi hoʻohālikelike me ka hoʻohana ʻana i ka polokalamu LAS Phase Expert.
E like me ka hoike ana ma ka fig. 1a, he microstructure eutectic i hoʻokumu ʻia ma waena o nā puke matrix o ka C-1 composite, kahi i manaʻo ʻia ai ka nui o ka matrix a me nā pae eutectic e like me 87.9 ± 0.47% a me 12.1% ± 0.51%. I loko o ka composite (C-2) i hōʻike ʻia ma ka Fig. 1b, ʻaʻohe hōʻailona o ka hopena eutectic i ka wā paʻa, a ʻike ʻia kahi microstructure ʻokoʻa loa mai ka C-1 composite. ʻOi aku ka maikaʻi o ka microstructure o ka C-2 composite a loaʻa nā ʻāpana lahilahi (carbides) i puʻunaue like ʻia i ka pae matrix (fcc). Kuhi ʻia nā hakina leo o ka matrix a me ka carbide ma 72 ± 1.69% a me 28 ± 1.69%. Ma waho aʻe o ka matrix a me ka carbide, ua loaʻa kahi māhele hou (silicida) ma ka C-3 composite, e like me ka mea i hōʻike ʻia ma ka Fig. 0.41%, 25.9 ± 0.53, a me 47.6 ± 0.34. Ua ʻike ʻia kekahi māhele hou (graphite) i loko o ka microstructure o ka C-4 composite; ua ʻike ʻia he ʻehā mau māhele. ʻO ka māhele graphite he ʻano poʻo honua ʻokoʻa me ka ʻokoʻa ʻeleʻele i nā kiʻi ʻikea a aia wale nō ma nā helu liʻiliʻi (ʻo ka hapa leo i manaʻo ʻia he 0.6 ± 0.30%) wale nō. I loko o nā hui C-5 a me C-6, ʻekolu mau ʻāpana wale nō i ʻike ʻia, a ʻike ʻia ka māhele graphite ʻokoʻa ʻeleʻele i loko o kēia mau composites ma ke ʻano o nā flakes. Ke hoʻohālikelike ʻia me nā graphite flakes ma Composite S-5, ʻo nā flakes graphite ma Composite S-6 ʻoi aku ka laulā, pōkole, a ʻoi aku ka maʻamau. Ua ʻike pū ʻia ka piʻi like ʻana o ka maʻiʻo graphite mai 14.9 ± 0.85% ma ka C-5 composite a hiki i kahi 17.4 ± 0.55% ma ka C-6 composite.
No ka noiʻi hou ʻana i ka microstructure kikoʻī a me ka haku mele ʻana o kēlā me kēia māhele i ka hui HEA, ua nānā ʻia nā laʻana me ka SEM, a ua hana pū ʻia ka nānā ʻana o ka helu EMF a me ka palapala ʻāina. Hōʻike ʻia nā hopena no ka hui C-1 ma ka fig. 2, kahi i ʻike maopopo ʻia ai ka hiki ʻana o nā hui eutectic e hoʻokaʻawale ana i nā ʻāpana o ka pae matrix nui. Hōʻike ʻia ka palapala ʻāina kemika o ka hui C-1 ma ke kiʻi 2c, kahi e ʻike ʻia ai ua puunaue like ʻia Co, Fe, Ni, a me Si i ka māhele matrix. Eia naʻe, ua ʻike ʻia kahi helu liʻiliʻi o ka Cr i loko o ka māhele matrix i hoʻohālikelike ʻia me nā mea ʻē aʻe o ke kumu HEA, e manaʻo ana ua hoʻopuehu ʻo Cr i waho o ka matrix. ʻO ka hoʻohui ʻana o ka pae eutectic keʻokeʻo i ke kiʻi SEM he waiwai i ka chromium a me ke kalapona, e hōʻike ana he chromium carbide. ʻO ka loaʻa ʻole o nā ʻāpana SiC discrete i ka microstructure, i hui pū ʻia me ka ʻike haʻahaʻa haʻahaʻa o ka chromium i loko o ka matrix a me ka hele ʻana o nā huila eutectic i loaʻa nā ʻāpana waiwai chromium, e hōʻike ana i ka decomposition piha o SiC i ka wā heheʻe. Ma muli o ka decomposition o SiC, hoʻoheheʻe ʻia ke silika ma ka pae matrix, a hui pū ke kalapona manuahi me ka chromium e hana i nā chromium carbide. E like me ka mea i ʻike ʻia, ʻo ke kalapona wale nō i hoʻoholo maikaʻi ʻia e ke ʻano EMF, a ua hōʻoia ʻia ka hoʻokumu ʻana o ka pae e ka ʻike ʻana i nā piko carbide hiʻohiʻona i nā kumu hoʻohālikelike X-ray.
(a) kiʻi SEM o ka laʻana S-1, (b) kiʻi i hoʻonui ʻia, (c) palapala ʻāina, (d) Nā hualoaʻa EMF ma nā wahi i hōʻike ʻia.
Hōʻike ʻia ka nānā ʻana o ka hui C-2 ma ka fig. 3. E like me ka nānā ʻana i ka microscopy optical, ua hōʻike ʻia ka hoʻokolohua SEM i kahi ʻano maikaʻi i haku ʻia i ʻelua mau ʻāpana wale nō, me ka loaʻa ʻana o kahi māhele lamellar lahilahi i puʻunaue like ʻia ma ka hale. pae matrix, a ʻaʻohe pae eutectic. Ua hōʻike ʻia ka hāʻawi ʻana i nā mea a me ka helu EMF o ka pae lamellar i kahi maʻiʻo kiʻekiʻe o Cr (melemele) a me C ('ōmaʻomaʻo) i kēia māhele, e hōʻike hou ana i ka decomposition o SiC i ka wā heheʻe a me ka pilina o ke kalapona i hoʻokuʻu ʻia me ka hopena chromium. . Hoʻokumu ka matrix VEA i kahi lamellar carbide phase. Ua hōʻike ʻia ka māhele ʻana o nā mea a me ka helu helu o ka pae matrix i ka hapa nui o ka cobalt, hao, nickel a me ke silikoni aia i loko o ka pae matrix.
(a) kiʻi SEM o ka laʻana S-2, (b) kiʻi i hoʻonui ʻia, (c) palapala ʻāina, (d) nā hualoaʻa EMF ma nā wahi i hōʻike ʻia.
Ua hōʻike ʻia nā haʻawina SEM o C-3 composites i ka hiki ʻana mai o nā ʻāpana hou i hoʻohui ʻia i ka carbide a me nā pae matrix. Hōʻike ka palapala ʻāina elemental (Fig. 4c) a me ka helu helu EMF (Fig. 4d) i ka waiwai o ka māhele hou i ka nickel, cobalt, a me ke silika.
(a) kiʻi SEM o ka laʻana S-3, (b) kiʻi i hoʻonui ʻia, (c) palapala ʻāina, (d) Nā hualoaʻa EMF ma nā wahi i hōʻike ʻia.
Hōʻike ʻia nā hopena o ka hōʻike SEM a me EMF o ka C-4 composite ma Fig. 5. Ma waho aʻe o nā ʻāpana ʻekolu i ʻike ʻia ma ka C-3 composite, ʻike pū ʻia ka noho ʻana o nā nodules graphite. ʻOi aku ka kiʻekiʻe o ka hakina leo o ka māhele waiwai silika ma mua o ko ka C-3 composite.
(a) kiʻi SEM o ka laʻana S-4, (b) kiʻi i hoʻonui ʻia, (c) palapala ʻāina, (d) nā hualoaʻa EMF ma nā wahi i hōʻike ʻia.
Hōʻike ʻia nā hopena o ka spectra SEM a me EMF o nā hui S-5 a me S-6 ma nā Kiʻi 1 a me 2. 6 a me 7. Ma waho aʻe o kahi helu liʻiliʻi o nā pōʻai, ua ʻike pū ʻia ka hele ʻana o nā flakes graphite. ʻOi aku ka nui o ka helu o nā graphite flakes a me ka hakina leo o ka māhele i loko o ka hui C-6 ma mua o ka hui C-5.
(a) kiʻi SEM o ka laʻana C-5, (b) nānā i hoʻonui ʻia, (c) palapala ʻāina kumu, (d) Nā hualoaʻa EMF ma nā wahi i hōʻike ʻia.
(a) kiʻi SEM o ka laʻana S-6, (b) kiʻi i hoʻonui ʻia, (c) palapala ʻāina, (d) Nā hualoaʻa EMF ma nā wahi i hōʻike ʻia.
Ua hoʻohana pū ʻia ka hoʻohālikelike ʻana i ka hoʻokumu ʻana o ke aniani o ka HEA composites me ka hoʻohana ʻana i nā ana XRD. Hōʻike ʻia ka hopena ma ke Kiʻi 8. Ma ke ʻano ʻokoʻa o ke kumu WEA (S-0), ʻike wale ʻia nā piko e pili ana i ka māhele fcc. Ua hōʻike ʻia nā hiʻohiʻona ʻokoʻa X-ray o nā composites C-1, C-2, a me C-3 i ka loaʻa ʻana o nā piko hou e pili ana i ka chromium carbide (Cr7C3), a ua emi ko lākou ikaika no nā laʻana C-3 a me C-4, i hōʻike ʻia. ʻo ia pū me ka EMF data no kēia mau laʻana. Ua ʻike ʻia nā kiʻekiʻe e pili ana i nā silicides Co / Ni no nā laʻana S-3 a me S-4, e like me nā hopena palapala palapala EDS i hōʻike ʻia ma nā Kiʻi 2 a me 3. E like me ka hōʻike ʻana ma ka Figure 3 a me ka Figure 4. Ua ʻike ʻia nā piko 5 a me S-6. pili i ka graphite.
Ua hōʻike ʻia nā hiʻohiʻona microstructural a me crystallographic o nā composites i hoʻomohala ʻia i ka decomposition o ka SiC i hoʻohui ʻia. Loaʻa kēia ma muli o ka loaʻa ʻana o ka chromium i ka matrix VEA. He pili ikaika loa ko Chromium no ke kalapona 54.55 a hoʻololi me ke kalapona manuahi e hana i ka carbide, e like me ka mea i hōʻike ʻia e ka emi ʻana o ka maʻiʻo chromium o ka matrix. Hele ʻo Si i ka māhele fcc ma muli o ka dissociation o SiC56. No laila,ʻo ka hoʻonuiʻana i ka hoʻohui o SiC i ke kumu HEA i alakaʻi i ka hoʻonuiʻana i ka nui o ka māhele carbide a me ka nui o ka Si free i ka microstructure. Ua ʻike ʻia ua waiho ʻia kēia Si hou i loko o ka matrix ma nā haʻahaʻa haʻahaʻa (i loko o nā hui S-1 a me S-2), ʻoiai ma nā kiʻekiʻe kiʻekiʻe (composites S-3 a i S-6) e hopena i ka hoʻoheheʻe cobalt hou. nickel silicide. ʻO ka enthalpy maʻamau o ka hoʻokumu ʻana o Co a me Ni silicides, i loaʻa ma ka synthesis pololei kiʻekiʻe-mehana calorimetry, ʻo ia -37.9 ± 2.0, -49.3 ± 1.3, -34.9 ± 1.1 kJ mol -1 no Co2Si, CoSi a me CoSi2, ʻoiai kēia mau mea. ʻO nā waiwai he - 50.6 ± 1.7 a me - 45.1 ± 1.4 kJ mol-157 no Ni2Si a me Ni5Si2. ʻOi aku ka haʻahaʻa o kēia mau waiwai ma mua o ka wela o ka hoʻokumu ʻana o SiC, e hōʻike ana i ka dissociation o SiC e alakaʻi ana i ka hoʻokumu ʻana o Co / Ni silicides he mea maikaʻi loa. I loko o nā hui ʻelua S-5 a me S-6, ua loaʻa nā silika manuahi ʻē aʻe, i hoʻopaʻa ʻia ma waho o ka hoʻokumu ʻana o ka silicide. Ua ʻike ʻia kēia kilika manuahi e kōkua i ka graphitization i ʻike ʻia ma nā kila maʻamau58.
Ke noiʻi ʻia nei nā ʻano mīkini o nā mea hoʻohui i hoʻoikaika ʻia i ka ceramic i hoʻokumu ʻia ma ka HEA e nā hoʻāʻo paʻa a me nā hoʻāʻo paʻakikī. Hōʻike ʻia nā ʻōkuhi koʻikoʻi o nā mea hoʻohui i kūkulu ʻia ma Fig. 9a, a ma ka Fig. 9b e hoike ana i ka scatterplot ma waena o ka ikaika hua kiko, ka ikaika hua, ka paakiki, a me ka elongation o na composites i kukuluia.
(a) Nā ʻōkuhi kānana compressive a me (b) scatterplots e hōʻike ana i ke koʻikoʻi hua kikoʻī, ka ikaika hua, ka paʻakikī a me ka elongation. E hoʻomaopopo he hōʻike S-0 a i S-4 wale nō ke hōʻike ʻia, no ka mea, loaʻa i nā specimen S-5 a me S-6 nā hemahema nui.
E like me ka ike ma ka fig. 9, ua hoʻonui ʻia ka ikaika hua mai 136 MPa no ke kumu VES (C-0) a i 2522 MPa no ka C-4 composite. Ke hoʻohālikelike ʻia i ka WPP kumu, ua hōʻike ka S-2 composite i kahi elongation maikaʻi loa i ka hāʻule ʻole o kahi o 37%, a ua hōʻike pū ʻia hoʻi nā koina ikaika kiʻekiʻe loa (1200 MPa). ʻO ka hui maikaʻi loa o ka ikaika a me ka ductility o kēia composite ma muli o ka hoʻomaikaʻi ʻana i ka microstructure holoʻokoʻa, me ka hāʻawi like ʻana o nā lamellae carbide maikaʻi i loko o ka microstructure, i manaʻo ʻia e kāohi i ka neʻe ʻana. He 1925 MPa a me 2522 MPa ka ikaika o ka hua o C-3 a me C-4. Hiki ke wehewehe ʻia kēia mau ikaika kiʻekiʻe e ka hapa kiʻekiʻe o ka carbide cemented a me ka silicide. Eia nō naʻe, ʻo ka hele ʻana o kēia mau ʻāpana i hopena i ka elongation ma ka haki ʻana o 7% wale nō. He convex nā kaha koʻikoʻi o ka base composite CoCrFeNi HEA (S-0) a me S-1, e hōʻike ana i ka hoʻoulu ʻana o ka hopena māhoe a i ʻole TRIP59,60. Ke hoʻohālikelike ʻia me ka laʻana S-1, ʻo ke koʻikoʻi koʻikoʻi o ka hāpana S-2 he ʻano concave ma kahi ʻano ma kahi o 10.20%, ʻo ia hoʻi, ʻo ka paheʻe dislocation maʻamau ke ʻano deformation nui o ka hāpana i kēia deformed state60,61 . Eia nō naʻe, ʻoi aku ka kiʻekiʻe o ka paʻakikī o kēia ʻano kikoʻī ma luna o kahi ākea nui, a ma nā ʻano kiʻekiʻe e ʻike ʻia ka hoʻololi ʻana i ka convexity (ʻoiai ʻaʻole hiki ke hoʻokaʻawale ʻia ma muli o ka hemahema o nā ukana compressive lubricated). ). ʻO nā mea hoʻohui C-3 a me C-4 he liʻiliʻi wale nō ka plasticity ma muli o ka loaʻa ʻana o nā hakina leo kiʻekiʻe o nā carbide a me nā silicides i loko o ka microstructure. ʻAʻole i hoʻokō ʻia nā hoʻāʻo hoʻoemi o nā laʻana o nā mea hoʻohui C-5 a me C-6 ma muli o nā hemahema nui o ka hoʻolei ʻana ma luna o kēia mau laʻana o nā composites (e nānā i ke kiʻi 10).
Nā Stereomicrographs o ka hoʻolei ʻana i nā hemahema (i hōʻike ʻia e nā pua ʻulaʻula) i nā laʻana o ka hui C-5 a me C-6.
Hōʻike ʻia nā hopena o ke ana ʻana i ka paʻakikī o nā composites VEA ma Fig. 9b. ʻO ka base WEA he 130 ± 5 HV ka paʻakikī, a me nā hōʻailona S-1, S-2, S-3 a me S-4 he mau waiwai paʻakikī o 250±10 HV, 275±10 HV, 570±20 HV a 755±20 HV. ʻO ka piʻi ʻana o ka paʻakikī i ʻaelike maikaʻi me ka hoʻololi ʻana i ka ikaika hua i loaʻa mai nā hoʻāʻo paʻa a pili pū me ka piʻi ʻana o ka nui o nā mea paʻa i loko o ka composite. Hōʻike pū ʻia ka ikaika hua kikoʻī i helu ʻia ma muli o ka haku mele ʻana o kēlā me kēia hāpana. 9b. Ma keʻano laulā, ʻike ʻia ka hui maikaʻi loa o ka ikaika hāʻawi (1200 MPa), ka paʻakikī (275 ± 10 HV), a me ka elongation pili i ka hāʻule (~37%) no ka C-2 composite.
Hōʻike ʻia ka hoʻohālikelike ʻana i ka ikaika hua a me ka elongation pili o ka composite i kūkulu ʻia me nā mea o nā papa like ʻole ma Fig. 11a. Ua hōʻike ʻia nā mea hoʻohui i hoʻokumu ʻia ma CoCrFeNi i kēia haʻawina i ka elongation kiʻekiʻe ma kēlā me kēia pae koʻikoʻi62. Hiki ke ʻike ʻia ʻo nā waiwai o nā mea hui HEA i hoʻomohala ʻia ma kēia haʻawina aia ma ka ʻāina i noho ʻole ʻia ma mua o ka ʻāpana o ka ikaika hua versus elongation. Eia kekahi, ʻo nā composites i hoʻomohala ʻia he ākea ākea o ka hui pū ʻana o ka ikaika (277 MPa, 1200 MPa, 1925 MPa a me 2522 MPa) a me ka elongation (> 60%, 37%, 7.3% a me 6.19%). He mea koʻikoʻi nō hoʻi ka ikaika o ka hoʻoulu ʻana i ke koho ʻana i nā mea no nā noi ʻenehana holomua63,64. Ma keia manao, ua hoike mai ka HEA composites o ka mea hou i keia manawa i ka hui maikai loa o ka ikaika a me ka elongation. ʻO kēia no ka mea ʻo ka hoʻohui ʻana o ka SiC haʻahaʻa haʻahaʻa e hopena i nā composites me ka ikaika hua kikoʻī kiʻekiʻe. ʻO ka ikaika hua kiko a me ka lōʻihi o ka HEA composites aia ma ka laulā like me HEA FCC a me ka refractory HEA, e like me ka mea i hōʻike ʻia ma ke kiʻi 11b. ʻO ka paʻakikī a me ka ikaika hoʻohua o nā mea hoʻohui i kūkulu ʻia ma ke ʻano like me nā aniani metala nui65 (Fig. 11c). Hōʻike ʻia nā aniani metala nui (BMS) e ka paʻakikī kiʻekiʻe a me ka ikaika hoʻohua, akā ua kaupalena ʻia ko lākou elongation66,67. Eia nō naʻe, ʻo ka paʻakikī a me ka ikaika hoʻohua o kekahi o nā hui HEA i kūkulu ʻia i loko o kēia haʻawina i hōʻike pū i ka elongation nui. No laila, ua hoʻoholo ʻia he hui kūʻokoʻa a ʻimi ʻia nā composites i hoʻomohala ʻia e VEA no nā ʻano hana like ʻole. Hiki ke wehewehe ʻia kēia hui ʻokoʻa o nā waiwai mechanical e ka hoʻopuehu like ʻana o nā carbide paʻakikī i hana ʻia i loko o ka FCC HEA matrix. Eia naʻe, ma ke ʻano o ka pahuhopu o ka loaʻa ʻana o kahi hui maikaʻi aʻe o ka ikaika, pono e nānā pono ʻia nā hoʻololi microstructural i loaʻa mai ka hoʻohui ʻana i nā ʻāpana seramika e pale aku i nā hemahema, e like me nā mea i loaʻa i ka S-5 a me S-6 composites, a ductility. kāne kāne.
Ua hoʻohālikelike ʻia nā hopena o kēia haʻawina me nā mea hana like ʻole a me nā HEA: (a) elongation versus yield strength62, (b) yield stress versus ductility63 a (c) yield strength versus hardness65.
Ua aʻo ʻia ka microstructure a me nā waiwai mechanical o kahi pūʻulu o HEA-ceramic composites i hoʻokumu ʻia ma ka ʻōnaehana HEA CoCrFeNi me ka hoʻohui ʻana o SiC a ua huki ʻia kēia mau hopena:
Hiki ke hoʻomohala maikaʻi ʻia nā composites entropy alloy kiʻekiʻe ma o ka hoʻohui ʻana iā SiC i ka CoCrFeNi HEA me ka hoʻohana ʻana i ke ʻano hoʻoheheʻe arc.
Hoʻoheheʻe ʻia ʻo SiC i ka wā o ka hoʻoheheʻe ʻana o ke arc, e alakaʻi ana i ka hoʻokumu ʻia ʻana o ka carbide, silicide a me ka graphite phases, ʻo ka hele ʻana a me ka hapa leo e hilinaʻi ʻia i ka nui o SiC i hoʻohui ʻia i ke kumu HEA.
Hōʻike ka HEA composites i nā waiwai mechanical maikaʻi loa, me nā waiwai i hāʻule i loko o nā wahi i noho ʻole ʻia ma mua ma ka ikaika o ka hoʻoulu ʻana me ka elongation plot. ʻO ka ikaika hua o ka HEA composite i hana ʻia me ka 6 wt% SiC ua ʻoi aku ma mua o ʻewalu mau manawa ma mua o ka HEA kumu me ka mālama ʻana i ka ductility 37%.
ʻO ka paʻakikī a me ka ikaika o ka hoʻoulu ʻana o HEA composites aia ma ka laulā o nā aniani metala nui (BMG).
Hōʻike nā mea i ʻike ʻia e hōʻike ana nā composites high-entropy alloy i kahi ala hoʻohiki i ka hoʻokō ʻana i kahi hui maikaʻi loa o nā waiwai metala-mechanical no nā noi hoʻolālā holomua.