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Ua manaʻo ʻia kahi ʻano hana hou e pili ana i ka hoʻoheheʻe laser koho e kāohi i ka microstructure o nā huahana i ke kaʻina hana hana. Hilinaʻi ka ʻano hana i ka hana ʻana o nā nalu ultrasonic ikaika kiʻekiʻe i loko o ka loko hoʻoheheʻe ʻia e ka irradiation laser modulated ikaika paʻakikī. Hōʻike nā haʻawina hoʻokolohua a me nā simulations helu he hiki ke hoʻohui pono ʻia kēia ʻano hana hoʻomalu i ka hoʻolālā ʻana o nā mīkini hoʻoheheʻe laser koho hou.
Ua ulu nui ka hana hoʻohui (AM) o nā ʻāpana ʻano paʻakikī i nā makahiki i hala iho nei. Eia nō naʻe, ʻoiai ke ʻano o nā kaʻina hana hana hoʻohui, me ka hoʻoheheʻe laser koho (SLM)1,2,3, ka waiho ʻana o ka metala laser pololei4,5,6, ka hoʻoheheʻe ʻana o ke kukuna electron7,8 a me nā mea ʻē aʻe9,10, hiki i nā ʻāpana ke hemahema. ʻO kēia ke kumu nui o nā ʻano kikoʻī o ke kaʻina hana hoʻopaʻa wai hoʻoheheʻe e pili ana me nā gradients thermal kiʻekiʻe, nā helu hoʻoluʻu kiʻekiʻe, a me ka paʻakikī o nā pōʻaiapuni hoʻomehana i nā mea hoʻoheheʻe a me ka hoʻoheheʻe hou ʻana11, kahi e alakaʻi ai i ka ulu ʻana o ka palaoa epitaxial a me ka porosity koʻikoʻi12,13. Hōʻike nā hopena, pono e kāohi i nā gradients thermal, nā helu hoʻoluʻu, a me ka haku mele alloy, a i ʻole e hoʻopili i nā haʻalulu kino hou ma o nā kahua o waho o nā waiwai like ʻole (e laʻa, ultrasound) e hoʻokō i nā ʻano palaoa equiaxed maikaʻi.
He nui nā puke paʻi e pili ana i ka hopena o ka mālama ʻana i ka haʻalulu ma ke kaʻina hana solidification i nā kaʻina hana hoʻolei maʻamau14,15. Eia nō naʻe, ʻo ka hoʻopili ʻana i kahi kahua waho i nā melts nui ʻaʻole ia e hana i ka microstructure mea i makemake ʻia. Inā liʻiliʻi ka nui o ka pae wai, loli nui ke kūlana. I kēia hihia, hoʻopilikia nui ke kahua waho i ke kaʻina hana solidification. Ua noʻonoʻo ʻia nā hopena electromagnetic i ka wā o nā kahua acoustic ikaika16,17,18,19,20,21,22,23,24,25,26,27, arc stirring28 a me oscillation29, pulsed plasma arcs30,31 a me nā ʻano hana ʻē aʻe32. E hoʻopili i ka substrate me ka hoʻohana ʻana i kahi kumu ultrasound kiʻekiʻe o waho (ma 20 kHz). ʻO ka hoʻomaʻemaʻe palaoa i hoʻokomo ʻia e ultrasound ua pili i ka hoʻonui ʻia ʻana o ka compositional subcooling zone ma muli o ka emi ʻana o ka gradient mahana a me ka hoʻonui ʻana o ka ultrasound e hana i nā crystallites hou ma o ka cavitation.
Ma kēia hana, ua noiʻi mākou i ka hiki ke hoʻololi i ke ʻano o ka palaoa o nā kila kila austenitic ma ka sonicating i ka loko i hoʻoheheʻe ʻia me nā nalu kani i hana ʻia e ka laser hoʻoheheʻe ponoʻī. ʻO ka modulation ikaika o ka hanana radiation laser ma ka medium absorbing light e hopena i ka hanauna o nā nalu ultrasonic, e hoʻololi i ka microstructure o ka mea. Hiki ke hoʻohui maʻalahi ʻia kēia modulation ikaika o ka radiation laser i loko o nā mīkini paʻi SLM 3D e kū nei. Ua hana ʻia nā hoʻokolohua ma kēia hana ma nā papa kila kila nona nā ʻili i hōʻike ʻia i ka radiation laser i hoʻololi ʻia i ka ikaika. No laila, ma ke ʻano loea, hana ʻia ka mālama ʻana i ka ʻili laser. Eia nō naʻe, inā hana ʻia kēlā ʻano mālama laser ma ka ʻili o kēlā me kēia papa, i ka wā o ke kūkulu ʻana o ka papa ma ka papa, ua hoʻokō ʻia nā hopena ma ka leo holoʻokoʻa a i ʻole ma nā ʻāpana i koho ʻia o ka leo. I nā huaʻōlelo ʻē aʻe, inā kūkulu ʻia ka ʻāpana papa ma ka papa, ʻo ka mālama ʻana i ka ʻili laser o kēlā me kēia papa ua like ia me ka "lāʻau nui laser".
ʻOiai i loko o ka ultrasonic horn-based ultrasonic therapy, ua hoʻolaha ʻia ka ikehu ultrasonic o ke alapine kani kū ma loko o ka ʻāpana, ʻoiai ʻo ka ikaika ultrasonic i hoʻokomo ʻia e ka laser ua hoʻopaʻa nui ʻia ma kahi kokoke i kahi i komo ai ka radiation laser. He paʻakikī ka hoʻohana ʻana i kahi sonotrode i loko o kahi mīkini fusion moena pauka SLM no ka mea ʻo ka ʻili luna o ka moena pauka i hōʻike ʻia i ka radiation laser e noho paʻa. Eia kekahi, ʻaʻohe pilikia mechanical ma ka ʻili luna o ka ʻāpana. No laila, kokoke ke kaumaha acoustic i ka zero a ʻo ka wikiwiki o ka ʻāpana he amplitude kiʻekiʻe loa ma luna o ka ʻili luna holoʻokoʻa o ka ʻāpana. ʻAʻole hiki i ke kaomi kani i loko o ka loko wai hoʻoheheʻe holoʻokoʻa ke ʻoi aku ma mua o 0.1% o ke kaomi kiʻekiʻe i hana ʻia e ke poʻo welding, no ka mea, ʻo ka nalu o nā nalu ultrasonic me ke alapine o 20 kHz i ke kila kila he \(\sim 0.3~\text {m}\), a ʻo ka hohonu maʻamau ka emi ma mua o \(\sim 0.3~\text {mm}\). No laila, hiki ke liʻiliʻi ka hopena o ka ultrasound ma ka cavitation.
Pono e hoʻomaopopo ʻia ʻo ka hoʻohana ʻana i ka radiation laser intensity-modulated i ka waiho ʻana o ka metala laser pololei he wahi hana ia o ka noiʻi35,36,37,38.
ʻO ka hopena wela o ka hopena o ka radiation laser ma ka medium ke kumu no ka aneane o nā ʻano hana laser āpau 39, 40 no ka hana ʻana i nā mea, e like me ka ʻoki ʻana41, ka hoʻopili ʻana, ka hoʻopaʻakikī ʻana, ka wili ʻana42, ka hoʻomaʻemaʻe ʻana i ka ʻili, ka hoʻohuihui ʻana i ka ʻili, ka polishing ʻili43, a pēlā aku. Ua hoʻoulu ka hana ʻana o ka laser i nā hoʻomohala hou i nā ʻano hana hana mea, a ua hōʻuluʻulu ʻia nā hopena mua ma nā loiloi he nui a me nā monographs44,45,46.
Pono e hoʻomaopopo ʻia ʻo kēlā me kēia hana paʻa ʻole ma ka medium, me ka hana lasing ma ka medium omo, e hopena i ka hoʻonāukiuki ʻana o nā nalu acoustic i loko me ka ʻoi aku a emi mai paha ka pono. I ka wā mua, ʻo ke kumu nui ma ka hoʻonāukiuki laser o nā nalu i loko o nā wai a me nā ʻano hana hoʻonāukiuki thermal like ʻole o ke kani (hoʻonui thermal, evaporation, hoʻololi leo i ka wā o ka hoʻololi ʻana o ka pae, contraction, etc.) 47, 48, 49. Nui nā monographs50, 51, 52 e hāʻawi i nā loiloi theoretical o kēia kaʻina hana a me kāna mau noi hana hiki.
Ua kūkākūkā ʻia kēia mau pilikia ma hope aku ma nā ʻaha kūkā like ʻole, a he mau noi ka hoʻonāukiuki laser o ka ultrasound ma nā noi ʻoihana o ka ʻenehana laser53 a me ka lāʻau lapaʻau54. No laila, hiki ke noʻonoʻo ʻia ua hoʻokumu ʻia ke kumumanaʻo kumu o ke kaʻina hana e hana ai ke kukui laser pulsed ma kahi medium absorbing. Hoʻohana ʻia ka nānā ʻana o ka laser ultrasonic no ka ʻike ʻana i nā hemahema o nā laʻana i hana ʻia e SLM55,56.
ʻO ka hopena o nā nalu haʻalulu i hana ʻia e ka laser ma luna o nā mea ke kumu o ka laser shock peening57,58,59, kahi i hoʻohana ʻia no ka mālama ʻana i ka ʻili o nā ʻāpana i hana ʻia me ka hoʻohui60. Eia nō naʻe, ʻoi aku ka maikaʻi o ka hoʻoikaika ʻana i ka haʻalulu laser ma nā pulse laser nanosecond a me nā ʻili i hoʻouka ʻia e ka mīkini (e laʻa, me kahi papa wai)59 no ka mea hoʻonui ka hoʻouka ʻana o ka mīkini i ke kaomi kiʻekiʻe.
Ua hana ʻia nā hoʻokolohua e noiʻi i nā hopena hiki o nā ʻano kino like ʻole ma ka microstructure o nā mea paʻa. Hōʻike ʻia ke kiʻikuhi hana o ka hoʻonohonoho hoʻokolohua ma ke Kiʻi 1. Ua hoʻohana ʻia kahi laser solid-state Nd:YAG pulsed e hana ana ma ke ʻano holo manuahi (pulse duration \(\tau _L \sim 150~\upmu \text {s}\ )). Hoʻouna ʻia kēlā me kēia pulse laser ma o kahi moʻo o nā kānana density neutral a me kahi ʻōnaehana papa beam splitter. Ma muli o ka hui pū ʻana o nā kānana density neutral, ʻokoʻa ka ikehu pulse ma ka pahuhopu mai \(E_L \sim 20~\text {mJ}\) a i \(E_L \sim 100~\text {mJ}\). Hānai ʻia ke kukuna laser i hōʻike ʻia mai ka beam splitter i kahi photodiode no ka loaʻa ʻana o ka ʻikepili like, a ʻelua mau calorimeters (photodiodes me ka manawa pane lōʻihi e ʻoi aku ana ma mua o \(1~\text {ms}\)) e hoʻoholo i ka hanana i a hōʻike ʻia mai ka pahuhopu, a ʻelua mau mika mana (photodiodes me ka pane pōkole manawa\(<10~\text {ns}\)) e hoʻoholo i ka mana optical i hōʻike ʻia a me ka mana optical i hōʻike ʻia. Ua hoʻoponopono ʻia nā Calorimeters a me nā mika mana e hāʻawi i nā waiwai i nā ʻāpana paʻa me ka hoʻohana ʻana i kahi mea ʻike thermopile Gentec-EO XLP12-3S-H2-D0 a me kahi aniani dielectric i kau ʻia ma kahi o ka laʻana. E hoʻoikaika i ke kukuna ma luna o ka pahuhopu me ka hoʻohana ʻana i kahi lens (Antireflection coating ma \(1.06 \upmu \text {m}\), focal length \(160~\text {mm}\)) a me kahi pūhaka kukuna ma ka ʻili pahuhopu 60– \(100~\upmu\text {m}\).
Kiʻikuhi hana o ka hoʻonohonoho hoʻokolohua: 1—laser; 2—kukui laser; 3—kānana mānoanoa kūlike ʻole; 4—photodiode i hoʻonohonoho ʻia; 5—mea hoʻokaʻawale kukuna; 6—diaphragm; 7—calorimeter o ke kukuna i hōʻike ʻia; 8 – calorimeter o ke kukuna i hōʻike ʻia; 9 – mika mana kukuna i hōʻike ʻia; 10 – mika mana kukuna i hōʻike ʻia; 11 – aniani kālele; 12 – aniani; 13 – laʻana; 14 – transducer piezoelectric broadband; 15 – mea hoʻololi 2D; 16 – microcontroller hoʻonohonoho; 17 – ʻāpana hoʻonohonoho; 18 – ʻōnaehana loaʻa kikohoʻe multi-channel me nā helu laʻana like ʻole; 19 – kamepiula pilikino.
Hoʻokō ʻia ka mālama ʻana o ka Ultrasonic penei. Hana ka laser ma ke ʻano holo manuahi; no laila, ʻo ka lōʻihi o ka pulse laser he \(\tau _L \sim 150~\upmu \text {s}\), nona nā lōʻihi he nui ma kahi o \(1.5~\upmu \text {s} \) kēlā me kēia. ʻO ke ʻano manawa o ka pulse laser a me kāna spectrum he envelope alapine haʻahaʻa a me ka modulation alapine kiʻekiʻe, me ka awelika alapine ma kahi o \(0.7~\text {MHz}\), e like me ka mea i hōʻike ʻia ma ke Kiʻi 2.- Hāʻawi ka envelope alapine i ka hoʻomehana a me ka hoʻoheheʻe ʻana a me ka mahu ʻana o ka mea, ʻoiai ʻo ka ʻāpana alapine kiʻekiʻe e hāʻawi i nā haʻalulu ultrasonic ma muli o ka hopena photoacoustic. Hoʻoholo nui ʻia ke ʻano nalu o ka pulse ultrasonic i hana ʻia e ka laser e ke ʻano manawa o ka ikaika o ka pulse laser. Mai \(7~\text {kHz}\) a i \ (2~\text {MHz}\), a ʻo ke alapine waena ʻo \(~ 0.7~\text {MHz}\). Ua hoʻopaʻa ʻia nā pulse acoustic ma muli o ka hopena photoacoustic me ka hoʻohana ʻana i nā transducers piezoelectric broadband i hana ʻia me nā kiʻiʻoniʻoni polyvinylidene fluoride. Hōʻike ʻia ke ʻano nalu i hoʻopaʻa ʻia a me kāna spectrum ma ke Kiʻi 2. Pono e hoʻomaopopo ʻia he ʻano maʻamau ke ʻano o nā pulse laser o kahi laser mode free-running.
Ka hoʻolaha manawa o ka ikaika o ka pulse laser (a) a me ka wikiwiki o ke kani ma ka ʻili hope o ka hāpana (b), nā spectra o ka pulse laser (c) a me ka pulse ultrasonic (d) i ʻawelike ʻia ma luna o 300 mau pulse laser (piʻo ʻulaʻula) no kahi pulse laser hoʻokahi (piʻo polū).
Hiki iā mākou ke hoʻokaʻawale maopopo i nā ʻāpana alapine haʻahaʻa a me ke alapine kiʻekiʻe o ka mālama ʻana i ka leo acoustic e pili ana i ka envelope alapine haʻahaʻa o ka pulse laser a me ka modulation alapine kiʻekiʻe. ʻOi aku ka lōʻihi o nā nalu o nā nalu acoustic i hana ʻia e ka envelope pulse laser ma mua o \(40~\text {cm}\); no laila, manaʻo ʻia ka hopena nui o nā ʻāpana alapine kiʻekiʻe o ka hōʻailona leo ma ka microstructure.
He paʻakikī nā kaʻina hana kino ma SLM a hana like ʻia ma nā unahi spatial a me ka manawa like ʻole. No laila, ʻoi aku ka kūpono o nā ʻano hana multi-scale no ka loiloi kumumanaʻo o SLM. Pono mua nā hiʻohiʻona makemakika e multi-physical. A laila hiki ke wehewehe pono ʻia nā mechanics a me thermophysics o kahi medium multiphase "solid-liquid melt" e launa pū ana me kahi lewa kinoea inert. Eia nā ʻano o nā ukana thermal mea ma SLM.
ʻO ka hoʻomehana ʻana a me ka hoʻomaʻalili ʻana a hiki i ka \(10^6~\text {K}/\text {s}\) /\text{ ma muli o ka hoʻomālamalama laser kūloko me nā mānoanoa mana a hiki i ka \(10^{13}~\text {W} cm}^2\).
ʻO ke kaʻina hana hoʻoheheʻe-paʻa ʻana ma waena o 1 a me \(10~\text {ms}\), ka mea e kōkua ai i ka paʻa wikiwiki ʻana o ka ʻāpana hoʻoheheʻe i ka wā e hoʻomaʻalili ai.
ʻO ka hoʻomehana wikiwiki ʻana o ka ʻili laʻana e hopena i ka hoʻokumu ʻia ʻana o nā koʻikoʻi thermoelastic kiʻekiʻe ma ka papa ʻili. ʻO ka hapa lawa (a hiki i ka 20%) o ka papa pauka e hoʻoheheʻe ikaika ʻia63, kahi e hopena ai i kahi ukana kaomi hou ma ka ʻili ma muli o ka ablation laser. ʻO ka hopena, hoʻopilikia nui ke koʻikoʻi i hoʻokomo ʻia i ka geometry ʻāpana, ʻoiai kokoke i nā kākoʻo a me nā mea hoʻonohonoho lahilahi. ʻO ka wikiwiki hoʻomehana kiʻekiʻe i ka pulsed laser annealing e hopena i ka hana ʻana o nā nalu koʻikoʻi ultrasonic e hoʻolaha mai ka ʻili a i ka substrate. I mea e loaʻa ai ka ʻikepili quantitative pololei ma ka hoʻolaha koʻikoʻi kūloko a me ke koʻikoʻi, hana ʻia kahi simulation mesoscopic o ka pilikia deformation elastic i hoʻopili ʻia i ka hoʻoili wela a me ka nuipa.
ʻO nā kaulike hoʻomalu o ke kumu hoʻohālike e komo pū ana me (1) nā kaulike hoʻoili wela paʻa ʻole kahi e hilinaʻi ai ka conductivity thermal i ke kūlana pae (pauka, heheʻe, polycrystalline) a me ka mahana, (2) nā fluctuations i ka deformation elastic ma hope o ka ablation continuum a me ka hoʻohālikelike hoʻonui thermoelastic. Hoʻoholo ʻia ka pilikia waiwai palena e nā kūlana hoʻokolohua. Ua wehewehe ʻia ka flux laser modulated ma ka ʻili laʻana. Hoʻokomo pū ka hoʻoluʻu convective i ka hoʻololi wela conductive a me ka flux evaporative. Ua wehewehe ʻia ka flux mass ma muli o ka helu ʻana o ke kaomi mahu saturated o ka mea evaporating. Hoʻohana ʻia ka pilina stress-strain elastoplastic kahi e kūlike ai ke kaumaha thermoelastic me ka ʻokoʻa o ka mahana. No ka mana nominal \(300~\text {W}\), alapine \(10^5~\text {Hz}\), coefficient intermittent 100 a me \(200~\upmu \text {m}\) o ke anawaena kukuna maikaʻi.
Hōʻike ka Kiʻi 3 i nā hopena o ka hoʻohālikelike helu o ka ʻāpana heheʻe me ka hoʻohana ʻana i kahi kumu hoʻohālike makemakika macroscopic. ʻO ke anawaena o ka ʻāpana fusion he \(200~\upmu \text {m}\) (\(100~\upmu \text { m}\) radius) a me \(40~\upmu \text {m}\) hohonu. Hōʻike nā hopena hoʻohālikelike e loli ana ka mahana o ka ʻili ma kahi kūloko me ka manawa e like me \(100~\text {K}\) ma muli o ke kumu intermittent kiʻekiʻe o ka modulation pulse. ʻO nā helu hoʻomehana \(V_h\) a me ka hoʻoluʻu \(V_c\) ma ke kauoha o \(10^7\) a me \(10^6~\text {K}/\text {s}\), kēlā me kēia. Ua kūlike kēia mau waiwai me kā mākou loiloi mua64. ʻO kahi ʻokoʻa kauoha o ka nui ma waena o \(V_h\) a me \(V_c\) e hopena i ka wela wikiwiki o ka papa ʻili, kahi i lawa ʻole ai ka hoʻoili wela i ka substrate e wehe i ka wela. No laila, ma \(t=26~\upmu \text {s}\) piʻi ka mahana o ka ʻili a hiki i ka \(4800~\text {K}\). Hiki i ka mahu ikaika o ka mea ke kumu i ke kaomi nui ʻana o ka ʻili o ka laʻana a hemo.
Nā hopena hoʻohālike helu o ka ʻāpana hoʻoheheʻe o ka pulse laser hoʻokahi annealing ma ka pā laʻana 316L. ʻO ka manawa mai ka hoʻomaka ʻana o ka pulse a hiki i ka hohonu o ka loko i hoʻoheheʻe ʻia e hiki ana i ka waiwai kiʻekiʻe loa ʻo \(180~\upmu\text {s}\). Hōʻike ka isotherm\(T = T_L = 1723~\text {K}\) i ka palena ma waena o nā pae wai a me nā pae paʻa. Pili nā isobars (nā laina melemele) i ke kaumaha hua i helu ʻia ma ke ʻano he hana o ka mahana ma ka ʻāpana aʻe. No laila, ma ke kikowaena ma waena o nā isolines ʻelua (isotherms\(T=T_L\) a me nā isobars\(\sigma =\sigma _V(T)\)), ua kau ʻia ka pae paʻa i nā ukana mechanical ikaika, hiki ke alakaʻi i nā loli i ka microstructure.
Ua wehewehe hou ʻia kēia hopena ma ke Kiʻi 4a, kahi i hoʻolālā ʻia ai ka pae kaomi ma ka ʻāpana heheʻe ma ke ʻano he hana o ka manawa a me ka mamao mai ka ʻili. ʻO ka mea mua, pili ke ʻano o ke kaomi i ka modulation o ka ikaika pulse laser i wehewehe ʻia ma ke Kiʻi 2 ma luna. Ua ʻike ʻia kahi kaomi kiʻekiʻe loa \text{s}\) ma kahi o \(10~\text {MPa}\) ma kahi o \(t=26~\upmu). ʻO ka lua, ʻo ka fluctuation o ke kaomi kūloko ma ke kiko kaohi he mau ʻano oscillation like me ke alapine o \(500~\text {kHz}\). ʻO ke ʻano kēia ua hoʻoulu ʻia nā nalu kaomi ultrasonic ma ka ʻili a laila hoʻolaha i loko o ka substrate.
Ua hōʻike ʻia nā ʻano i helu ʻia o ka ʻāpana deformation kokoke i ka ʻāpana heheʻe ma ke Kiʻi 4b. Hoʻopuka ka ablation laser a me ke kaumaha thermoelastic i nā nalu deformation elastic e pālahalaha ana i loko o ka substrate. E like me ka mea i ʻike ʻia mai ke kiʻi, aia ʻelua mau pae o ka hanauna stress. I ka wā mua o \(t < 40~\upmu \text {s}\), piʻi ka stress Mises i \(8~\text {MPa}\) me kahi modulation e like me ke kaomi o ka ʻili. Hiki mai kēia stress ma muli o ka ablation laser, a ʻaʻohe stress thermoelastic i ʻike ʻia ma nā wahi mana no ka mea ua liʻiliʻi loa ka ʻāpana i hoʻopilikia ʻia e ka wela mua. Ke hoʻokuʻu ʻia ka wela i loko o ka substrate, hoʻopuka ka wahi mana i ke kaumaha thermoelastic kiʻekiʻe ma luna o \(40~\text {MPa}\).
ʻO nā pae koʻikoʻi i hoʻololi ʻia i loaʻa he hopena koʻikoʻi ia ma ka pilina paʻa-wai a hiki ke lilo i ʻano hoʻomalu e hoʻomalu ana i ke ala paʻa. ʻO ka nui o ka ʻāpana deformation he 2 a 3 mau manawa ʻoi aku ka nui ma mua o ka ʻāpana melting. E like me ka mea i hōʻike ʻia ma ke Kiʻi 3, ua hoʻohālikelike ʻia kahi o ka isotherm melting a me ka pae koʻikoʻi e like me ke koʻikoʻi yield. ʻO ke ʻano kēia, hāʻawi ka irradiation laser pulsed i nā ukana mechanical kiʻekiʻe ma nā wahi kūloko me ke anawaena kūpono ma waena o 300 a me \(800~\upmu \text {m}\) ma muli o ka manawa koke.
No laila, ʻo ka modulation paʻakikī o ka pulsed laser annealing e alakaʻi ai i ka hopena ultrasonic. He ʻokoʻa ke ala koho microstructure inā hoʻohālikelike ʻia me ka SLM me ka ʻole o ka hoʻouka ultrasonic. ʻO nā ʻāpana paʻa ʻole i hoʻololi ʻia e alakaʻi i nā pōʻaiapuni periodic o ka compression a me ke kīkoʻo ʻana i ka pae paʻa. No laila, hiki ke hoʻokumu ʻia nā palena palaoa hou a me nā palena subgrain. No laila, hiki ke hoʻololi ʻia nā waiwai microstructural, e like me ka mea i hōʻike ʻia ma lalo nei. Hāʻawi nā hopena i loaʻa i ka hiki ke hoʻolālā i kahi prototype SLM i hoʻokele ʻia e ka ultrasound modulation pulse. I kēia hihia, hiki ke hoʻokaʻawale ʻia ka inductor piezoelectric 26 i hoʻohana ʻia ma kahi ʻē.
(a) Kaomi ma ke ʻano he hana o ka manawa, i helu ʻia ma nā mamao like ʻole mai ka ʻili 0, 20 a me \(40~\upmu \text {m}\) ma ke axis o ka symmetry.(b) ʻO ke koʻikoʻi Von Mises e pili ana i ka manawa i helu ʻia i loko o kahi matrix paʻa ma nā mamao 70, 120 a me \(170~\upmu \text {m}\) mai ka ʻili laʻana.
Ua hana ʻia nā hoʻokolohua ma nā papa kila kila AISI 321H me nā ana \(20\times 20\times 5~\text {mm}\). Ma hope o kēlā me kēia pulse laser, neʻe ka papa \(50~\upmu \text {m}\), a ʻo ka pūhaka kukuna laser ma ka ʻili o ka pahuhopu ma kahi o \(100~\upmu \text {m}\). A hiki i ʻelima mau hele ʻana o ke kukuna ma hope e hana ʻia ma ke ala like e hoʻoulu ai i ka hoʻoheheʻe hou ʻana o ka mea i hana ʻia no ka hoʻomaʻemaʻe ʻana i ka palaoa. I nā hihia āpau, ua sonicated ʻia ka ʻāpana i hoʻoheheʻe hou ʻia, ma muli o ka ʻāpana oscillatory o ka radiation laser. ʻO ka hopena kēia i ka emi ʻana ma mua o 5-fold ma ka awelika o ka ʻāpana palaoa. Hōʻike ka Kiʻi 5 pehea e loli ai ka microstructure o ka ʻāpana i hoʻoheheʻe ʻia e ka laser me ka helu o nā pōʻaiapuni hoʻoheheʻe hou ʻana (passes).
ʻO nā Subplots (a,d,g,j) a me (b,e,h,k) - microstructure o nā ʻāpana i hoʻoheheʻe ʻia e ka laser, nā subplots (c,f,i,l) - ka hoʻolaha ʻana o nā ʻāpana kala. Hōʻike ka shading i nā ʻāpana i hoʻohana ʻia e helu i ka histogram. Pili nā kala i nā ʻāpana palaoa (e nānā i ka pā kala ma ka piko o ka histogram. Pili nā Subplots (ac) i ke kila kila i mālama ʻole ʻia, a pili nā subplots (df), (gi), (jl) i 1, 3 a me 5 mau hoʻoheheʻe hou ʻia.
ʻOiai ʻaʻole e loli ka ikehu pulse laser ma waena o nā hala ma hope, ua like ka hohonu o ka ʻāpana heheʻe. No laila, ua "uhi" loa ke kahawai ma hope i ka mea ma mua. Eia nō naʻe, hōʻike ka histogram e emi ana ka awelika a me ka median grain area me ka hoʻonui ʻana i ka nui o nā hala. Hōʻike paha kēia e hana ana ka laser ma ka substrate ma mua o ka heheʻe.
Hiki ke hoʻomaʻalili ʻia ka palaoa e ka hoʻomaʻalili wikiwiki ʻana o ka loko i hoʻoheheʻe ʻia65. Ua hana ʻia kekahi hoʻokolohua ʻē aʻe kahi i hōʻike ʻia ai nā ʻili o nā papa kila kila (321H a me 316L) i ka radiation laser nalu mau i ka lewa (Kiʻi 6) a me ka vacuum (Kiʻi 7). ʻO ka mana laser awelika (300 W a me 100 W, kēlā me kēia) a me ka hohonu o ka loko i hoʻoheheʻe ʻia ua kokoke i nā hopena hoʻokolohua o ka laser Nd:YAG ma ke ʻano holo manuahi. Eia nō naʻe, ua ʻike ʻia kahi ʻano kolamu maʻamau.
ʻO ke ʻano liʻiliʻi o ka ʻāpana i hoʻoheheʻe ʻia e ka laser o kahi laser nalu hoʻomau (mana mau 300 W, wikiwiki scan 200 mm/s, kila kila AISI 321H).
(a) Microstructure a me (b) nā kiʻi diffraction electron backscatter o ka ʻāpana i hoʻoheheʻe ʻia e ka laser i loko o ka vacuum me kahi laser nalu hoʻomau (100 W mana mau, 200 mm/s wikiwiki scan, AISI 316L kila kila)\ (\sim 2~\text {mbar}\).
No laila, ua hōʻike maopopo ʻia he hopena koʻikoʻi ka modulation paʻakikī o ka ikaika o ka pulse laser i ka microstructure hopena. Manaʻo mākou he ʻano mechanical kēia hopena a hana ʻia ma muli o ka hanauna o nā haʻalulu ultrasonic e hoʻolaha ana mai ka ʻili irradiated o ka heheʻe hohonu i loko o ka laʻana. Ua loaʻa nā hopena like ma 13, 26, 34, 66, 67 me ka hoʻohana ʻana i nā transducers piezoelectric waho a me nā sonotrodes e hāʻawi ana i ka ultrasound ikaika kiʻekiʻe i nā mea like ʻole me Ti-6Al-4V alloy 26 a me ke kila kila 34 ka hopena o. Ua kuhi ʻia ke ʻano hana hiki ke hana penei. Hiki i ka ultrasound ikaika ke hana i ka cavitation acoustic, e like me ka mea i hōʻike ʻia ma ka ultrafast in situ synchrotron X-ray imaging. ʻO ka hiolo ʻana o nā pehu cavitation e hoʻopuka i nā nalu haʻalulu i loko o ka mea i hoʻoheheʻe ʻia, nona ke kaomi mua e hiki aku ana ma kahi o \(100~\text {MPa}\)69. Hiki i kēlā mau nalu haʻalulu ke ikaika e hoʻolaha i ka hoʻokumu ʻana o nā nuclei paʻa-phase koʻikoʻi i nā wai nui, e hoʻopilikia ana i ka ʻano palaoa columnar maʻamau o hana hoʻohui papa-ma-papa.
Maanei, ke hāpai nei mākou i kahi ʻano hana ʻē aʻe e kuleana no ka hoʻololi ʻana i ke ʻano ma o ka sonication ikaika. Ma hope koke o ka hoʻopaʻa ʻana, aia ka mea i kahi mahana kiʻekiʻe kokoke i ka wahi heheʻe a he haʻahaʻa loa ka hoʻoluhi hua. Hiki i nā nalu ultrasonic ikaika ke hoʻololi i ke kahe plastik i ke ʻano o ka palaoa o ka mea wela, paʻa wale. Eia nō naʻe, loaʻa nā ʻikepili hoʻokolohua hilinaʻi ma ka hilinaʻi mahana o ke kaumaha hua ma \(T\lesssim 1150~\text {K}\) (e nānā i ke Kiʻi 8). No laila, no ka hoʻāʻo ʻana i kēia kuhiakau, ua hana mākou i nā simulations molecular dynamics (MD) o kahi hui Fe-Cr-Ni e like me ke kila AISI 316 L i mea e loiloi ai i ke ʻano o ke kaumaha hua kokoke i ka wahi heheʻe. No ka helu ʻana i ke kaumaha hua, ua hoʻohana mākou i ke ʻano hoʻomaha hoʻomaha MD shear stress i hōʻike kikoʻī ʻia ma 70, 71, 72, 73. No nā helu pilina interatomic, ua hoʻohana mākou i ka Embedded Atomic Model (EAM) mai 74. Ua hana ʻia nā simulations MD me ka hoʻohana ʻana i nā code LAMMPS 75,76. E paʻi ʻia nā kikoʻī o nā simulations MD ma kahi ʻē. ʻO ka MD Ua hōʻike ʻia nā hopena helu o ke koʻikoʻi hua ma ke ʻano he hana o ka mahana ma ke Kiʻi 8 me nā ʻikepili hoʻokolohua i loaʻa a me nā loiloi ʻē aʻe77,78,79,80,81,82.
ʻO ke kaumaha hua no ke kila kila austenitic AISI 316 a me ka hoʻohuihui kumu hoʻohālike e kūʻē i ka mahana no nā simulations MD. Nā ana hoʻokolohua mai nā kuhikuhi: (a) 77, (b) 78, (c) 79, (d) 80, (e) 81. e nānā i. ʻO (f)82 kahi kumu hoʻohālike empirical o ka hilinaʻi ʻana o ka stress-temperature no ke ana ʻana o ke kaumaha in-line i ka wā o ka hana hoʻohui laser-assisted. Ua hōʻailona ʻia nā hopena o nā simulations MD nui ma kēia haʻawina ʻo \(\vartriangleleft\) no kahi kristal hoʻokahi kīnā ʻole a me \(\vartriangleright\) no nā hua finite e noʻonoʻo ana i ka nui o ka hua ma o ka pilina Hall-Petch Dimensions\(d = 50~\upmu \text {m}\).
Hiki ke ʻike ʻia ma \(T>1500~\text {K}\) hāʻule ke koʻikoʻi o ka yield ma lalo o \(40~\text {MPa}\). Ma ka ʻaoʻao ʻē aʻe, ua wānana nā kuhi e ʻoi aku ka nui o ka amplitude ultrasonic i hana ʻia e ka laser ma mua o \(40~\text {MPa}\) (e nānā i ke Kiʻi 4b), kahi i lawa ai e hoʻoulu i ke kahe plastik i loko o ka mea wela i hoʻopaʻa ʻia.
Ua noiʻi ʻia ma ke ʻano hoʻokolohua ke kūkulu ʻia ʻana o ka microstructure o ke kila kila austenitic 12Cr18Ni10Ti (AISI 321H) i ka wā o ka SLM me ka hoʻohana ʻana i kahi kumu laser pulsed intensity-modulated paʻakikī.
Ua ʻike ʻia ka emi ʻana o ka nui o nā hua i loko o ka ʻāpana heheʻe laser ma muli o ka hoʻoheheʻe hou ʻana o ka laser ma hope o 1, 3 a i ʻole 5 mau hala ʻana.
Hōʻike ka hoʻohālikelike macroscopic ʻo ka nui i manaʻo ʻia o ka ʻāpana kahi e hiki ai i ka deformation ultrasonic ke hoʻopilikia maikaʻi i ke alo solidification a hiki i ka \(1~\text {mm}\).
Hōʻike ke kumu hoʻohālike MD microscopic ua hoʻemi nui ʻia ka ikaika hua o ke kila kila austenitic AISI 316 i \(40~\text {MPa}\) kokoke i ke kiko heheʻe.
Hōʻike nā hopena i loaʻa i kahi ʻano hana no ka kaohi ʻana i ka microstructure o nā mea me ka hoʻohana ʻana i ka hana laser modulated paʻakikī a hiki ke lawelawe ma ke ʻano he kumu no ka hana ʻana i nā hoʻololi hou o ke ʻano hana pulsed SLM.
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