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Kucetywa indlela entsha esekelwe ekunyibilikeni kwelaser ekhethiweyo ukulawula ulwakhiwo lwemveliso kwinkqubo yokuvelisa. Le ndlela ixhomekeke ekudalweni kwamaza e-ultrasonic anamandla aphezulu kwidama elinyibilikisiweyo nge-complex irradiation yelaser eguquguqukayo ngamandla. Izifundo zovavanyo kunye nokulinganisa amanani zibonisa ukuba le ndlela yokulawula inokwenzeka ngobuchwephesha kwaye ingadityaniswa ngempumelelo kuyilo lwemishini yokunyibilikisa ilaser ekhethiweyo yanamhlanje.
Ukwenziwa kwezinto ezongezelelekileyo (AM) kwiindawo ezimile okwe-complex kukhule kakhulu kwiminyaka yakutshanje. Nangona kunjalo, nangona kukho iinkqubo ezahlukeneyo zokwenziwa kwezinto ezongezelelekileyo, kuquka ukunyibilika kwe-laser ekhethiweyo (SLM)1,2,3, ukufakwa kwesinyithi se-laser ngqo4,5,6, ukunyibilika kwe-electron beam7,8 kunye nezinye9,10, iiNdawo zisenokuba neziphene. Oku kungenxa yeempawu ezithile zenkqubo yokuqina kwedama elinyibilikisiweyo elinxulunyaniswa ne-thermal gradients ephezulu, amazinga aphezulu okupholisa, kunye nobunzima bemijikelo yokufudumeza kwizinto zokunyibilika kunye nokunyibilikisa11, ezikhokelela ekukhuleni kwengqolowa ye-epitaxial kunye ne-porosity ebalulekileyo12,13. Iziphumo zibonisa ukuba, kuyimfuneko ukulawula i-thermal gradients, amazinga okupholisa, kunye nokwakheka kwe-alloy, okanye ukusebenzisa izothuso ezongezelelweyo zomzimba ngokusebenzisa amasimi angaphandle eempawu ezahlukeneyo (umz., i-ultrasound) ukufezekisa izakhiwo zengqolowa ezilinganayo.
Iimpapasho ezininzi zijongene nefuthe lonyango lokungcangcazela kwinkqubo yokuqina kwiinkqubo zokubumba eziqhelekileyo14,15. Nangona kunjalo, ukusebenzisa intsimi yangaphandle kwi-bulk melts akuvelisi isakhiwo esifunekayo sezinto ezincinci. Ukuba umthamo wesigaba solwelo mncinci, imeko itshintsha kakhulu. Kule meko, intsimi yangaphandle ichaphazela kakhulu inkqubo yokuqina. Iziphumo ze-electromagnetic ziye zaqwalaselwa ngexesha leentsimi ezibukhali ze-acoustic16,17,18,19,20,21,22,23,24,25,26,27, i-arc stirging28 kunye ne-oscillation29, i-pulsed plasma arcs30,31 kunye nezinye iindlela32. Ncamathisela kwi-substrate usebenzisa umthombo wangaphandle we-ultrasound ophezulu (kwi-20 kHz). Ukulungiswa kweenkozo ezibangelwa yi-ultrasound kubangelwe kukwanda kwendawo yokupholisa ye-compositional ngenxa yokunciphisa i-gradient yobushushu kunye nokuphuculwa kwe-ultrasound ukuvelisa iikristali ezintsha nge-cavitation.
Kulo msebenzi, siphande ukuba kunokwenzeka ukutshintsha isakhiwo seentsimbi ze-austenitic stainless steels ngokufaka i-sonicate echibini elinyibilikisiweyo ngamaza esandi aveliswa yi-melting laser ngokwayo. Ukuguqulwa kwamandla kwesiganeko se-laser radiation kwi-medium efunxa ukukhanya kubangela ukuveliswa kwamaza e-ultrasonic, atshintsha isakhiwo sezinto. Olu tshintsho loxinzelelo lwe-laser radiation lunokudityaniswa ngokulula kwiiprinta ze-SLM 3D ezikhoyo. Uvavanyo kulo msebenzi lwenziwe kwiiplate zentsimbi engagqwaliyo apho ubuso bazo buvezwe kwi-laser-modulated intensity-modulated radiation. Ngoko ke, ngobuchwephesha, unyango lwe-laser surface luyenziwa. Nangona kunjalo, ukuba unyango olunjalo lwe-laser lwenziwa kumphezulu womaleko ngamnye, ngexesha lokwakhiwa komaleko ngomaleko, iziphumo kwi-volume yonke okanye kwiindawo ezikhethiweyo ze-volume ziyafezekiswa. Ngamanye amazwi, ukuba inxalenye yakhiwe umaleko ngomaleko, unyango lwe-laser surface lomaleko ngamnye lulingana "nonyango lwe-laser volume".
Ngelixa kunyango lwe-ultrasonic olusekwe kwi-ultrasonic, amandla e-ultrasonic esandi esimiyo asasazwa kulo lonke icandelo, ngelixa i-ultrasound enamandla e-laser ebangelwa yi-laser igxile kakhulu kufutshane nendawo apho i-laser radiation ifunxwa khona. Ukusebenzisa i-sonotrode kumatshini we-SLM powder bed fusion kuyinkimbinkimbi kuba umphezulu we-powder bed ovezwe kwi-laser radiation kufuneka uhlale ungashukumi. Ukongeza, akukho xinzelelo loomatshini kumphezulu wenxalenye. Ke ngoko, uxinzelelo lwe-acoustic lusondele kwi-zero kwaye isantya se-particle sine-amplitude ephezulu kumphezulu wonke wenxalenye. Uxinzelelo lwesandi ngaphakathi kwechibi lonke elinyibilikisiweyo alunakudlula i-0.1% yoxinzelelo oluphezulu oluveliswa yintloko ye-welding, kuba ubude bamaza e-ultrasonic ane-frequency ye-20 kHz kwintsimbi engagqwali yi-\(\sim 0.3~\text {m}\), kwaye ubunzulu buhlala bungaphantsi kune-\(\sim 0.3~\text {mm}\). Ke ngoko, isiphumo se-ultrasound kwi-cavitation sinokuba sincinci.
Kufuneka kuqatshelwe ukuba ukusetyenziswa kwemitha yelaser eguqulwe ngamandla kwi-laser metal deposition ngqo yindawo esebenzayo yophando35,36,37,38.
Isiphumo sobushushu sesiganeko semitha yelaser kwisixhobo sisiseko phantse kuzo zonke iindlela zelaser 39, 40 zokucubungula izinto, ezinje ngokusika 41, ukuwelda, ukuqinisa, ukubhola 42, ukucoca umphezulu, ukuxutywa komphezulu, ukupolisha umphezulu 43, njl. Ukuveliswa kwelaser kukhuthaze uphuhliso olutsha kwiindlela zokucubungula izinto, kwaye iziphumo zokuqala zishwankathelwe kuphononongo oluninzi kunye nee-monograph 44, 45, 46.
Kufuneka kuqatshelwe ukuba nasiphi na isenzo esingamiyo kwi-medium, kuquka isenzo sokuhlala ixesha elide kwi-absorbing medium, siphumela ekuvuseleleni amaza e-acoustic kuyo ngokusebenza okuncinci okanye okuncinci. Ekuqaleni, ingqwalasela ephambili yayikukuvuselela amaza nge-laser kulwelo kunye neendlela ezahlukeneyo zokuvuselela ubushushu zesandi (ukwandiswa kobushushu, ukufuma, utshintsho lomthamo ngexesha lotshintsho lwesigaba, ukucotha, njl.njl.) 47, 48, 49. Ii-monographs ezininzi50, 51, 52 zibonelela ngohlalutyo lwethiyori lwale nkqubo kunye nokusetyenziswa kwayo okunokwenzeka.
Le miba kamva yaxoxwa kwiingqungquthela ezahlukeneyo, kwaye ukukhuthazwa kwe-ultrasound nge-laser kunezicelo kuzo zombini izicelo zobugcisa be-laser53 kunye nezonyango54. Ke ngoko, kunokucingelwa ukuba ingcamango esisiseko yenkqubo apho ukukhanya kwe-laser okushukumayo kusebenza khona kwindawo yokufunxa sele imiselwe. Ukuhlolwa kwe-ultrasound nge-laser kusetyenziswa ukufumanisa iziphene zeesampuli ezenziwe nge-SLM55,56.
Isiphumo samaza othuko adalwa yilaser kwizinto sisiseko se-laser shock peening57,58,59, ekwasetyenziselwa unyango lomphezulu weendawo ezenziwe ngokongeza60. Nangona kunjalo, ukuqinisa i-laser shock kusebenza kakhulu kwi-nanosecond laser pulses kunye neendawo ezifakwe ngoomatshini (umz., ngomaleko wolwelo)59 kuba umthwalo woomatshini wonyusa uxinzelelo oluphezulu.
Kwenziwe uvavanyo ukuze kuphandwe iziphumo ezinokubakho zamacandelo ahlukeneyo omzimba kwisakhiwo sezinto eziqinileyo. Umzobo osebenzayo wokuseta uvavanyo uboniswe kuMfanekiso 1. Kusetyenziswe i-pulsed Nd:YAG solid-state laser esebenza kwi-free-running mode (ixesha le-pulse \(\tau _L \sim 150~\upmu \text {s}\ )) . I-laser pulse nganye idlula kuthotho lwee-neutral density filters kunye nenkqubo ye-beam splitter plate. Ngokuxhomekeke ekudibaneni kwee-neutral density filters, amandla e-pulse kwithagethi ayahluka ukusuka ku-\(E_L \sim 20~\text {mJ}\) ukuya ku-\(E_L \sim 100~\text {mJ}\) . I-laser beam ebonakaliswa kwi-beam splitter inikwa i-photodiode ukuze kufunyanwe idatha ngaxeshanye, kwaye ii-calorimeters ezimbini (ii-photodiodes ezinexesha elide lokuphendula elidlula ku-\(1~\text {ms}\)) zisetyenziselwa ukufumanisa isiganeko ukuya kwaye sibonakaliswe kwithagethi, kunye neemitha ezimbini zamandla (ii-photodiodes ezinempendulo emfutshane). amaxesha\(<10~\text {ns}\)) ukufumanisa isiganeko kunye namandla okukhanya abonakalisiweyo. Iikhalorimitha kunye neemitha zamandla zilinganisiwe ukunika amaxabiso kwiiyunithi ezipheleleyo kusetyenziswa isixhobo sokubona i-thermopile iGentec-EO XLP12-3S-H2-D0 kunye nesibuko se-dielectric esifakwe kwindawo yesampulu. Gxilisa umqadi kwithagethi usebenzisa ilensi (i-Antireflection coating kwi \(1.06 \upmu \text {m}\), ubude befocal \(160~\text {mm}\)) kunye nesinqe se-beam kumphezulu wethagethi 60– \(100~\upmu\text {m}\).
Umzobo wesicwangciso osebenzayo wokuseta uvavanyo: 1—ilaser; 2—umqadi welaser; 3—isihluzo soxinano olungathathi cala; 4—i-photodiode ehambelanayo; 5—isihlukanisi seebham; 6—i-diaphragm; 7—ii-calorimeter zomqadi wesiganeko; 8—ii-calorimeter zomqadi obonakalisiweyo; 9 – imitha yamandla omqadi wesiganeko; 10 – imitha yamandla omqadi obonakalisiweyo; 11 – ilensi yokugxila; 12 – isibuko; 13 – isampulu; 14 – i-transducer ye-piezoelectric ebanzi; 15 – i-converter ye-2D; 16 – i-microcontroller yokubeka indawo; 17 – iyunithi yokuvumelanisa; 18 – inkqubo yokufumana idijithali yeziteshi ezininzi enamazinga ahlukeneyo okuthatha iisampulu; 19 – ikhompyutha yomntu.
Unyango lwe-ultrasonic lwenziwa ngolu hlobo lulandelayo. I-laser isebenza kwimo yokusebenza ngokukhululekileyo; ngoko ke ubude be-laser pulse yi-\(\tau _L \sim 150~\upmu \text {s}\), equlathe ubude obuninzi obumalunga ne-\(1.5~\upmu \text {s} \) nganye. Ubume bexesha le-laser pulse kunye ne-spectrum yayo buquka i-envelope ye-frequency ephantsi kunye ne-high-frequency modulation, kunye ne-frequency ephakathi ye-\(0.7~\text {MHz}\), njengoko kubonisiwe kuMfanekiso 2.- I-envelope ye-frequency ibonelela ngokufudumala kunye nokunyibilika okulandelayo kunye nokuphuma komphunga kwezinto, ngelixa icandelo le-frequency ephezulu libonelela ngokungcangcazela kwe-ultrasonic ngenxa yesiphumo se-photoacoustic. Uhlobo lwe-wave ye-ultrasonic pulse eveliswa yi-laser lumiselwa kakhulu yimo yexesha lobunzulu be-laser pulse. Iqala kwi-\(7~\text {kHz}\) ukuya kwi-\ (2~\text {MHz}\), kwaye i-center frequency yi-\(~ 0.7~\text {MHz}\). Ii-acoustic pulses ngenxa yesiphumo se-photoacoustic zirekhodwe kusetyenziswa ii-transducers ze-broadband piezoelectric ezenziwe ngeefilimu ze-polyvinylidene fluoride. I-waveform erekhodiweyo kunye ne-spectrum yayo iboniswe kuMfanekiso 2. Kufuneka kuqatshelwe ukuba imo yee-laser pulses ifana ne-laser ye-free-running mode.
Ukusasazwa kwexeshana kobunzulu be-laser pulse (a) kunye nesantya sesandi kumphezulu ongasemva wesampuli (b), ii-spectra ze-laser pulse (c) kunye ne-ultrasonic pulse (d) zijikeleze ngaphezu kwama-300 e-laser pulses (i-red curve) kwi-laser pulse enye (i-blue curve).
Singahlula ngokucacileyo izinto ezisetyenziswa rhoqo kunye nezisetyenziswa rhoqo kakhulu zonyango lwe-acoustic ezihambelana ne-low-frequency envelope ye-laser pulse kunye ne-high-frequency modulation, ngokulandelelana. Amaza obude bamaza asetyenziswa rhoqo adalwa yi-laser pulse envelope adlula \(40~\text {cm}\); ke ngoko, isiphumo esiphambili sezinto ezisetyenziswa rhoqo kakhulu ze-broadband zesignali ye-acoustic kwisakhiwo se-microstructure kulindeleke.
Iinkqubo ze-physical kwi-SLM zintsonkothile kwaye zenzeka ngaxeshanye kwiisikali ezahlukeneyo zendawo nezexesha. Ke ngoko, iindlela ze-multi-scale zilungele kakhulu uhlalutyo lwethiyori lwe-SLM. Iimodeli zezibalo kufuneka ekuqaleni zibe ze-multi-physical. I-mechanics kunye ne-thermophysics ye-multi-phase medium "solid-liquid melt" edibana nomoya wegesi ongasebenziyo emva koko zinokuchazwa ngempumelelo. Iimpawu zemithwalo yobushushu bezinto kwi-SLM zezi zilandelayo.
Amanqanaba okufudumeza nokupholisa afikelela kwi \(10^6~\text {K}/\text {s}\) /\text{ ngenxa yokukhanya kwelaser okukwindawo ethile kunye noxinano lwamandla ukuya kuthi ga kwi \(10^{13}~\text {W} cm}^2\).
Umjikelo wokunyibilika-ukuqina uhlala phakathi kwe-1 kunye ne-\(10~\text {ms}\), nto leyo enegalelo ekuqineni ngokukhawuleza kwendawo yokunyibilika ngexesha lokupholisa.
Ukufudumeza ngokukhawuleza komphezulu wesampuli kubangela ukwakheka koxinzelelo oluphezulu lwe-thermoelastic kumaleko womphezulu. Inxalenye eyaneleyo (ukuya kuthi ga kwi-20%) yomaleko womgubo iyaphuma ngamandla, nto leyo ebangela umthwalo owongezelelweyo woxinzelelo kumphezulu ngenxa yokususwa kwelaser. Ngenxa yoko, uxinzelelo olubangelwayo luphazamisa kakhulu i-geometry yenxalenye, ingakumbi kufutshane neenkxaso kunye nezinto ezincinci zesakhiwo. Izinga eliphezulu lokufudumeza kwi-pulsed laser annealing liphumela ekuvelisweni kwamaza oxinzelelo lwe-ultrasonic asasazeka ukusuka kumphezulu ukuya kwi-substrate. Ukuze kufunyanwe idatha echanekileyo yobungakanani malunga noxinzelelo lwendawo kunye nokusasazwa koxinzelelo, kwenziwa ukulinganisa kwe-mesoscopic kwengxaki yokuguqulwa kwe-elastic edityaniswe nobushushu kunye nokudluliselwa kobunzima.
Ii-equations ezilawulayo zemodeli ziquka (1) ii-equations zokudlulisa ubushushu ezingazinzanga apho ukuhanjiswa kobushushu kuxhomekeke kwimeko yesigaba (umgubo, ukunyibilika, i-polycrystalline) kunye nobushushu, (2) ukuguquguquka kwe-elastic deformation emva kokususwa okuqhubekekayo kunye ne-thermoelastic expansion equation. Ingxaki yexabiso lomda imiselwa ziimeko zovavanyo. I-modulated laser flux ichazwa kumphezulu wesampuli. Ukupholisa kweConvective kubandakanya ukutshintshiselana kobushushu okuqhubayo kunye ne-evaporative flux. I-mass flux ichazwa ngokusekelwe ekubalweni koxinzelelo lomphunga olugcweleyo lwezinto ezikhupha umphunga. Ubudlelwane be-elastoplastic stress-strain busetyenziswa apho uxinzelelo lwe-thermoelastic luhambelana nomahluko wobushushu. Ngamandla aqhelekileyo \(300~\text {W}\), i-frequency \(10^5~\text {Hz}\), i-intermittent coefficient 100 kunye \(200~\upmu \text {m}\ ) yobubanzi be-beam esebenzayo.
Umfanekiso 3 ubonisa iziphumo zokulinganisa ngenani lendawo enyibilikisiweyo kusetyenziswa imodeli yemathematika ye-macroscopic. Ububanzi bendawo yokudibanisa yi-\(200~\upmu \text {m}\) (\(100~\upmu \text {m}\) radius) kunye ne-\(40~\upmu \text {m}\) ubunzulu. Iziphumo zokulinganisa zibonisa ukuba ubushushu bomphezulu buyahluka ngokwendawo ngokwexesha njenge-\(100~\text {K}\) ngenxa ye-intermittent factor ephezulu ye-pulse modulation. Amazinga okufudumala \(V_h\) kunye nokupholisa \(V_c\) akwi-order ye-\(10^7\) kunye ne-\(10^6~\text {K}/\text {s}\), ngokwahlukeneyo. La maxabiso avumelana kakuhle nohlalutyo lwethu lwangaphambili64. Umahluko wolandelelwano phakathi kwe-\(V_h\) kunye ne-\(V_c\) uphumela ekutshiseni ngokukhawuleza komaleko womphezulu, apho ukuhanjiswa kobushushu kwi-substrate kungonelanga ukususa ubushushu. Ke ngoko, kwi-\(t=26~\upmu \text {s}\) ubushushu bomphezulu bufikelela kwincopho ephezulu njenge \(4800~\text {K}\). Ukufuma ngamandla kwezinto kunokubangela ukuba umphezulu wesampuli ucinezelwe kakhulu kwaye uxobuke.
Iziphumo zokulinganisa amanani zommandla wokunyibilika kwe-single laser pulse annealing kwipleyiti yesampulu ye-316L. Ixesha ukusuka ekuqaleni kwe-pulse ukuya kubunzulu bedama elinyibilikisiweyo elifikelela kwixabiso eliphezulu yi-\(180~\upmu\text {s}\). I-isotherm\(T = T_L = 1723~\text {K}\) imele umda phakathi kwezigaba zolwelo kunye neziqinileyo. Ii-isobars (imigca etyheli) zihambelana noxinzelelo lwe-yield olubalwe njengomsebenzi wobushushu kwicandelo elilandelayo. Ke ngoko, kwicandelo eliphakathi kwe-isolines ezimbini (isotherms\(T=T_L\) kunye ne-isobars\(\sigma =\sigma _V(T)\)), isigaba esiqinileyo siphantsi kwemithwalo enamandla yoomatshini, enokukhokelela kutshintsho kwisakhiwo se-microstructure.
Esi siphumo sichazwe ngakumbi kuMfanekiso 4a, apho inqanaba loxinzelelo kwindawo enyibilikisiweyo lidweliswe njengomsebenzi wexesha kunye nomgama ukusuka kumphezulu. Okokuqala, ukuziphatha koxinzelelo kunxulumene nokuguqulwa kobunzulu be-laser pulse echazwe kuMfanekiso 2 ngasentla. Uxinzelelo oluphezulu \text{s}\) olumalunga ne \(10~\text {MPa}\) lubonwe malunga ne \(t=26~\upmu). Okwesibini, ukuguquguquka koxinzelelo lwendawo kwindawo yokulawula kuneempawu ezifanayo ze-oscillation njenge-frequency ye \(500~\text {kHz}\). Oku kuthetha ukuba amaza oxinzelelo lwe-ultrasonic enziwa kumphezulu aze asasazeke kwi-substrate.
Iimpawu ezibaliweyo zommandla wokuguquguquka kufutshane nendawo yokunyibilika ziboniswe kwiFig. 4b. Ukususwa kwelaser kunye noxinzelelo lwe-thermoelastic kuvelisa amaza okuguquguquka kwe-elastic asasazeka kwi-substrate. Njengoko kunokubonwa kumfanekiso, kukho amanqanaba amabini okuvelisa uxinzelelo. Ngexesha lesigaba sokuqala se-\(t < 40~\upmu \text {s}\), uxinzelelo lwe-Mises lunyuka luye kwi-\(8~\text {MPa}\) nge-modulation efana noxinzelelo lomphezulu. Olu xinzelelo lwenzeka ngenxa yokususwa kwelaser, kwaye akukho xinzelelo lwe-thermoelastic olubonwe kwiindawo zokulawula kuba indawo yokuqala echaphazeleke bubushushu yayincinci kakhulu. Xa ubushushu busasazeka kwi-substrate, indawo yokulawula ivelisa uxinzelelo oluphezulu lwe-thermoelastic ngaphezulu kwe-\(40~\text {MPa}\).
Amanqanaba oxinzelelo olulungisiweyo afunyenweyo anempembelelo enkulu kwi-interface ye-solid-liquid kwaye isenokuba yindlela yokulawula elawula indlela yokuqina. Ubungakanani bendawo yokuguqulwa bubukhulu ngokuphindwe kabini ukuya kathathu kunobo bendawo yokunyibilika. Njengoko kubonisiwe kuMfanekiso 3, indawo ye-isotherm yokunyibilika kunye nenqanaba loxinzelelo elilingana noxinzelelo lwe-yield ziyathelekiswa. Oku kuthetha ukuba i-pulsed laser irradiation inika imithwalo ephezulu yoomatshini kwiindawo ezikufutshane ezinobubanzi obusebenzayo phakathi kwama-300 kunye ne-\(800~\upmu \text {m}\) kuxhomekeke kwixesha elikhawulezileyo.
Ke ngoko, ukuguquguquka okuntsonkothileyo kwe-pulsed laser annealing kukhokelela kwisiphumo se-ultrasonic. Indlela yokukhetha isakhiwo se-microstructure yahlukile xa ithelekiswa ne-SLM ngaphandle kokulayisha kwe-ultrasonic. Iindawo ezingazinzanga eziguquliweyo zikhokelela kwimijikelo yexeshana yokucinezelwa kunye nokolulwa kwisigaba esiqinileyo. Ke ngoko, ukwakheka kwemida emitsha yeenkozo kunye nemida ye-subgrain kuba yinto enokwenzeka. Ke ngoko, iipropati zesakhiwo se-microstructure zinokutshintshwa ngabom, njengoko kubonisiwe ngezantsi. Izigqibo ezifunyenweyo zibonelela ngethuba lokuyila iprototype ye-SLM eqhutywa yi-pulse modulation-induced ultrasound. Kule meko, i-piezoelectric inductor 26 esetyenziswa kwenye indawo ingakhutshelwa ngaphandle.
(a) Uxinzelelo njengomsebenzi wexesha, lubalwa kumgama owahlukileyo ukusuka kumphezulu 0, 20 kunye \(40~\upmu \text {m}\) ecaleni kwe-axis yokulingana.(b) Uxinzelelo lwe-Von Mises oluxhomekeke kwixesha lubalwa kwi-matrix eqinileyo kumgama 70, 120 kunye \(170~\upmu \text {m}\) ukusuka kumphezulu wesampuli.
Uvavanyo lwenziwe kwiipleyiti zentsimbi engagqwaliyo ze-AISI 321H ezinobukhulu \(20\times 20\times 5~\text {mm}\). Emva kokutshaya kwelaser nganye, ipleyiti ishukuma \(50~\upmu \text {m}\), kwaye isinqe selaser kumphezulu ekujoliswe kuwo simalunga \(100~\upmu \text {m}\). Kuye kudlule imiqadi emihlanu elandelayo kwindlela efanayo ukuze kukhuthazwe ukunyibilika kwezinto ezicutshungulwayo ukuze kuphuculwe ingqolowa. Kuzo zonke iimeko, indawo enyibilikisiweyo yenziwe nge-sonicated, kuxhomekeke kwinxalenye ye-oscillatory yemitha yelaser. Oku kubangela ukwehla okuphindwe kahlanu kwindawo ephakathi kwengqolowa. Umfanekiso 5 ubonisa indlela isakhiwo se-microstructure sendawo enyibilikisiweyo ngelaser esitshintsha ngayo ngenani lemijikelo elandelayo yokunyibilika (iipase).
Iiploti ezincinci (a,d,g,j) kunye (b,e,h,k) – isakhiwo esincinci seendawo ezinyibilikisiweyo nge-laser, iiploti ezincinci (c,f,i,l) – ukusasazwa kwendawo yeenkozo ezinemibala. Umthunzi umele amasuntswana asetyenziselwa ukubala i-histogram. Imibala ihambelana nemimandla yeenkozo (jonga umgca wombala phezulu kwe-histogram. Iiploti ezincinci (ac) zihambelana nentsimbi engatyiwayo engacocwanga, kwaye iiploti ezincinci (df), (gi), (jl) zihambelana ne-1, 3 kunye ne-5 remelts.
Ekubeni amandla e-laser pulse engatshintshi phakathi kokudlula okulandelayo, ubunzulu bendawo enyibilikisiweyo buyafana. Ngoko ke, itshaneli elandelayo "igubungela" ngokupheleleyo eyangaphambili. Nangona kunjalo, i-histogram ibonisa ukuba indawo ye-mean kunye ne-median grain iyancipha ngokunyuka kwenani lokudlula. Oku kunokubonisa ukuba i-laser isebenza kwi-substrate endaweni yokunyibilika.
Ukulungiswa kweenkozo kunokubangelwa kukupholisa ngokukhawuleza kwechibi elinyibilikisiweyo65. Olunye useto lovavanyo lwenziwe apho imiphezulu yeepleyiti zentsimbi engagqwaliyo (321H kunye ne-316L) yavezwa kwimitha yelaser yamaza aqhubekayo emoyeni (Umzobo 6) kunye ne-vacuum (Umzobo 7). Amandla aphakathi elaser (300 W kunye ne-100 W, ngokulandelanayo) kunye nobunzulu bechibi elinyibilikisiweyo zisondele kwiziphumo zovavanyo zelaser ye-Nd:YAG kwimo yokusebenza ngokukhululekileyo. Nangona kunjalo, isakhiwo esiqhelekileyo sekholamu sabonwa.
Ulwakhiwo oluncinci lwendawo enyibilikiswe yilaser yelaser yamaza aqhubekayo (amandla angaguqukiyo angama-300 W, isantya sokuskena esingama-200 mm/s, intsimbi engagqwaliyo ye-AISI 321H).
(a) Isakhiwo esincinci kunye (b) imifanekiso ye-electron backscatter diffraction yendawo enyibilikiswe yilaser kwi-vacuum ene-continuous wave laser (amandla angaguqukiyo ayi-100 W, isantya sokuskena se-200 mm/s, intsimbi engagqwaliyo ye-AISI 316L)\ (\sim 2~\text {mbar}\).
Ngoko ke, kuboniswe ngokucacileyo ukuba ukuguquguquka okuntsonkothileyo kokuqina kwe-laser pulse kunempembelelo ebalulekileyo kwisakhiwo esiphumayo. Sikholelwa ukuba esi siphumo senziwe ngoomatshini kwaye senzeka ngenxa yokuveliswa kweentshukumo ze-ultrasonic ezisasazeka kumphezulu okhanyayo we-melt nzulu ukuya kwisampulu. Iziphumo ezifanayo zifunyenwe kwi-13, 26, 34, 66, 67 kusetyenziswa ii-transducers zangaphandle ze-piezoelectric kunye nee-sonotrodes ezibonelela nge-ultrasound enamandla kakhulu kwizinto ezahlukeneyo kuquka i-Ti-6Al-4V alloy 26 kunye ne-stainless steel 34 isiphumo. Indlela enokwenzeka iqikelelwa ngolu hlobo lulandelayo. I-ultrasound enamandla inokubangela i-acoustic cavitation, njengoko kuboniswe kwi-ultrafast in situ synchrotron X-ray imaging. Ukuwa kwee-cavitation bubbles kuvelisa amaza okwethutyana kwizinto ezinyibilikisiweyo, apho uxinzelelo lwazo lwangaphambili lufikelela malunga ne-\(100~\text {MPa}\)69. Amaza okwethutyana anjalo anokuba namandla ngokwaneleyo ukukhuthaza ukwakheka kwee-nuclei ze-solid-phase ezinobukhulu obubalulekileyo kwii-bulk liquids, okuphazamisa isakhiwo se-columnar grain esiqhelekileyo se Ukwenziwa kwezongezo ngomaleko ngomaleko.
Apha, sicebisa enye indlela enoxanduva lokuguqulwa kwesakhiwo nge-sonication enamandla. Ngokukhawuleza emva kokuqina, izinto zikwiqondo lobushushu eliphezulu elikufutshane nendawo yokunyibilika kwaye zinoxinzelelo oluphantsi kakhulu lwemveliso. Amaza amakhulu e-ultrasonic anokubangela ukuhamba kweplastiki ukutshintsha isakhiwo sengqolowa sezinto ezishushu, eziqinisiweyo nje. Nangona kunjalo, idatha yovavanyo ethembekileyo malunga nokuxhomekeka kobushushu koxinzelelo lwemveliso ifumaneka kwi-\(T\lesssim 1150~\text {K}\) (jonga uMfanekiso 8). Ke ngoko, ukuvavanya le ngcamango, senze ii-simulations ze-molecular dynamics (MD) ze-Fe-Cr-Ni composition efana ne-AISI 316 L steel ukuze kuvavanywe ukuziphatha koxinzelelo lwemveliso kufutshane nendawo yokunyibilika. Ukubala uxinzelelo lwemveliso, sisebenzise indlela yokuphumla koxinzelelo lwe-MD echazwe kwi-70, 71, 72, 73. Kwiindlela zokubala i-interatomic interaction, sisebenzise i-Embedded Atomic Model (EAM) evela kwi-74. Ii-simulations ze-MD zenziwe kusetyenziswa iikhowudi ze-LAMMPS 75,76. Iinkcukacha zee-simulations ze-MD ziya kupapashwa kwenye indawo. Iziphumo zokubala ze-MD zemveliso uxinzelelo njengomsebenzi wobushushu luboniswe kwiFig. 8 kunye nedatha yovavanyo ekhoyo kunye nolunye uvavanyo77,78,79,80,81,82.
Uxinzelelo lwemveliso kwi-AISI grade 316 austenitic stainless steel kunye nokwakheka kwemodeli ngokuchasene nobushushu kwiimodeli ze-MD. Umlinganiselo wovavanyo oluvela kwiireferensi: (a) 77, (b) 78, (c) 79, (d) 80, (e) 81. bhekisa kwi.(f)82 yimodeli esetyenziswayo yokuxhomekeka koxinzelelo lwemveliso kubushushu bokulinganisa uxinzelelo olukwi-line ngexesha lokwenziwa kwe-additive encediswa yi-laser. Iziphumo zeemodeli ze-MD ezinkulu kolu phononongo zichazwe njenge-\(\vartriangleleft\) yekristale enye engenasiphako engenasiphako kunye ne-\(\vartriangleright\) yeenkozo ezilinganiselweyo kuthathelwa ingqalelo ubungakanani bengqolowa ephakathi ngokusebenzisa i-Hall-Petch relation Dimensions\(d = 50~\upmu \text {m}\).
Kuyabonakala ukuba kwi-\(T>1500~\text {K}\) uxinzelelo lwe-yield luyehla ngaphantsi kwe-\(40~\text {MPa}\). Kwelinye icala, uqikelelo luqikelela ukuba i-amplitude ye-ultrasonic eyenziwe nge-laser idlula i-\(40~\text {MPa}\) (jonga uMzobo 4b), owaneleyo ukukhuthaza ukuhamba kweplastiki kwizinto ezishushu ezisandula ukuqina.
Ukwakheka kwesakhiwo esincinci sentsimbi engagqwali ye-austenitic ye-12Cr18Ni10Ti (AISI 321H) ngexesha le-SLM kuphandwe ngovavanyo kusetyenziswa umthombo we-laser oshukunyisiweyo we-intensity-modulated complex.
Ukuncipha kobukhulu beenkozo kwindawo yokunyibilika kwelaser kufunyenwe ngenxa yokunyibilika kwelaser rhoqo emva kokudlula oku-1, oku-3 okanye oku-5.
Imodeli ye-macroscopic ibonisa ukuba ubungakanani obuqikelelweyo bendawo apho ukuguquguquka kwe-ultrasonic kunokuchaphazela kakuhle umphambili wokuqina bufikelela kwi-\(1~\text {mm}\).
Imodeli ye-MD encinci ibonisa ukuba amandla okuvelisa i-AISI 316 austenitic stainless steel ancitshiswe kakhulu ukuya kwi-\(40~\text {MPa}\) kufutshane nendawo yokunyibilika.
Iziphumo ezifunyenweyo zibonisa indlela yokulawula ulwakhiwo lwezixhobo ngokusebenzisa i-complex modulated laser processing kwaye ingasebenza njengesiseko sokwenza utshintsho olutsha kwindlela ye-pulsed SLM.
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