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Kuphakanyiswa indlela entsha esekelwe ekuncibilikisweni kwe-laser ekhethiwe ukulawula isakhiwo esincane semikhiqizo enkambisweni yokukhiqiza. Le ndlela incike ekudalweni kwamagagasi e-ultrasonic anamandla aphezulu echibini elincibilikisiwe ngemisebe ye-laser eyinkimbinkimbi eguquliwe. Izifundo zokuhlola kanye nokulingisa ngezinombolo kubonisa ukuthi le ndlela yokulawula ingenzeka ngobuchwepheshe futhi ingafakwa ngempumelelo ekwakhiweni kwemishini yokuncibilikisa i-laser yanamuhla ekhethiwe.
Ukukhiqizwa kwe-additive (AM) kwezingxenye ezibunjwe ngendlela eyinkimbinkimbi kukhule kakhulu emashumini eminyaka amuva nje. Kodwa-ke, naphezu kwezinhlobonhlobo zezinqubo zokukhiqiza ze-additive, okuhlanganisa ukuncibilika kwe-laser ekhethiwe (SLM)1,2,3, ukufakwa kwensimbi ye-laser eqondile4,5,6, ukuncibilika kwe-electron beam7,8 nabanye9,10, Izingxenye zingase zibe nephutha. Lokhu kungenxa kakhulu yezici ezithile zenqubo yokuqina kwe-pool encibilikisiwe ehlotshaniswa nama-gradients aphezulu okushisa, amazinga aphezulu okupholisa, kanye nobunzima bemijikelezo yokushisa ezintweni zokuncibilikisa nokubuyisela emuva11, okuholela ekukhuleni kwe-epitaxial grain kanye ne-porosity ebalulekile12,13. Imiphumela ikhombisa ukuthi , kuyadingeka ukulawula ama-gradients okushisa, amazinga okupholisa, kanye nokwakheka kwe-alloy, noma ukusebenzisa ama-shocks engeziwe ngokomzimba ngokusebenzisa amasimu angaphandle ezakhiwo ezahlukahlukene (isb., i-ultrasound) ukuze kufezwe izakhiwo ze-grain ezilinganayo.
Izincwadi eziningi ziphathelene nomphumela wokwelashwa kokudlidliza enkambisweni yokuqina kwezinqubo ezivamile zokubumba14,15. Kodwa-ke, ukusebenzisa insimu yangaphandle ekuncibilikeni okukhulu akukhiqizi isakhiwo esincane sezinto ezidingekayo. Uma ivolumu yesigaba soketshezi incane, isimo sishintsha kakhulu. Kulokhu, insimu yangaphandle ithinta kakhulu inqubo yokuqina kwesakhiwo. Imiphumela ye-electromagnetic iye yacatshangelwa ngesikhathi samasimu aqinile e-acoustic16,17,18,19,20,21,22,23,24,25,26,27, i-arc stirging28 kanye ne-oscillation29, i-pulsed plasma arcs30,31 kanye nezinye izindlela32. Namathisela ku-substrate usebenzisa umthombo wangaphandle we-ultrasound onamandla aphezulu (ku-20 kHz). Ukulungiswa kokusanhlamvu okubangelwa yi-ultrasound kubangelwa ukwanda kwendawo yokupholisa okuhlanganisiwe ngenxa yokwehla kwe-gradient yokushisa kanye nokuthuthukiswa kwe-ultrasound ukukhiqiza amakristalu amasha nge-cavitation.
Kulo msebenzi, sihlole ukuthi kungenzeka yini ukushintsha isakhiwo sezinhlamvu zezinsimbi ezingagqwali ze-austenitic ngokufaka i-sonicate echibini elincibilikisiwe ngamaza omsindo akhiqizwa yi-laser encibilikayo uqobo. Ukuguqulwa kwamandla kwesigameko sokukhanya kwe-laser endaweni ebamba ukukhanya kuphumela ekwakhiweni kwamaza e-ultrasonic, okushintsha isakhiwo sezinto ezibonakalayo. Lokhu kuguqulwa kwamandla kwemisebe ye-laser kungafakwa kalula kumaphrinta e-SLM 3D akhona. Ukuhlolwa kulo msebenzi kwenziwe kumapuleti ensimbi angagqwali lapho ubuso bawo buvezwe khona emisebeni ye-laser eguquliwe ngamandla. Ngakho-ke, ngokobuchwepheshe, ukwelashwa komhlaba nge-laser kuyenziwa. Kodwa-ke, uma ukwelashwa okunjalo nge-laser kwenziwa ebusweni besendlalelo ngasinye, ngesikhathi sokwakheka kwesendlalelo ngesendlalelo, imiphumela kuyo yonke ivolumu noma ezingxenyeni ezikhethiwe zevolumu iyafezwa. Ngamanye amazwi, uma ingxenye yakhiwe isendlalelo ngesendlalelo, ukwelashwa komhlaba nge-laser wesendlalelo ngasinye kufana "nokwelashwa kwevolumu ye-laser".
Ngenkathi ekwelashweni kwe-ultrasonic okusekelwe ku-ultrasonic, amandla e-ultrasonic egagasi lomsindo elimile asatshalaliswa kulo lonke ingxenye, kuyilapho ukuqina kwe-ultrasonic okubangelwa yi-laser kugxile kakhulu eduze nendawo lapho imisebe ye-laser imuncwa khona. Ukusebenzisa i-sonotrode emshinini wokuhlanganisa umbhede we-SLM powder bed kuyinkimbinkimbi ngoba ubuso obuphezulu bombhede we-powder obuvezwe emisebeni ye-laser kufanele buhlale bumile. Ngaphezu kwalokho, akukho ukucindezeleka komshini ebusweni obuphezulu bengxenye. Ngakho-ke, ukucindezeleka kwe-acoustic kuseduze no-zero futhi ijubane lezinhlayiya linokuphakama okuphezulu phezu kobuso obuphezulu bengxenye. Ukucindezela komsindo ngaphakathi kwechibi lonke elincibilikisiwe akukwazi ukudlula u-0.1% wokucindezela okuphezulu okukhiqizwa ikhanda lokushisela, ngoba ubude bamagagasi e-ultrasonic obunemvamisa engu-20 kHz ngensimbi engagqwali buyi-\(\sim 0.3~\text {m}\), kanti ukujula kuvame ukuba ngaphansi kuka-\(\sim 0.3~\text {mm}\). Ngakho-ke, umphumela we-ultrasound ku-cavitation ungaba mncane.
Kufanele kuqashelwe ukuthi ukusetshenziswa kwemisebe ye-laser eguquliwe ngamandla ekufakweni kwensimbi ye-laser ngqo kuyindawo esebenzayo yocwaningo35,36,37,38.
Umphumela wokushisa wesigameko sokukhishwa kwemisebe ye-laser endaweni yokuxhumana uyisisekelo cishe sazo zonke izindlela ze-laser 39, 40 zokucubungula izinto, njengokusika 41, ukushisela, ukuqinisa, ukubhoboza 42, ukuhlanza ubuso, ukuhlanganisa ubuso, ukupholisha ubuso 43, njll. Ukusungulwa kwe-laser kwavuselela intuthuko entsha kumasu okucubungula izinto, futhi imiphumela yokuqala ifingqiwe kuzibuyekezo eziningi kanye nama-monograph 44, 45, 46.
Kufanele kuqashelwe ukuthi noma yisiphi isenzo esingami endaweni, okuhlanganisa isenzo sokuhlala isikhathi eside endaweni emuncayo, kuholela ekuvuselelweni kwamagagasi e-acoustic kuyo ngokusebenza kahle noma kancane. Ekuqaleni, ukugxila okuyinhloko kwakusekuvuselelweni kwamagagasi nge-laser koketshezi kanye nezindlela ezahlukene zokuvuselela umsindo (ukwanda kokushisa, ukuhwamuka, ushintsho lwevolumu ngesikhathi sokuguquka kwesigaba, ukufinyela, njll.) 47, 48, 49. Ama-monograph amaningi50, 51, 52 anikeza ukuhlaziywa kwethiyori kwale nqubo kanye nezicelo zayo ezingokoqobo ezingaba khona.
Lezi zindaba kamuva zaxoxwa ngazo emihlanganweni eyahlukene, futhi ukuvusa nge-laser kwe-ultrasound kunezisetshenziswa kokubili ekusetshenzisweni kwezimboni kobuchwepheshe be-laser53 kanye nezokwelapha54. Ngakho-ke, kungacatshangwa ukuthi umqondo oyisisekelo wenqubo lapho ukukhanya kwe-laser okushukunyiswayo kusebenza khona endaweni emuncayo ususunguliwe. Ukuhlolwa kwe-ultrasonic ye-laser kusetshenziselwa ukuthola amaphutha amasampula enziwe nge-SLM55,56.
Umphumela wamagagasi okushaqisa akhiqizwa yi-laser ezintweni zokwakha uyisisekelo sokushaqisa kwe-laser57,58,59, okusetshenziselwa nokwelashwa kwendawo yezingxenye ezenziwe ngokungeziwe60. Kodwa-ke, ukuqinisa ukushaqisa kwe-laser kusebenza kakhulu kuma-pulse e-laser e-nanosecond kanye nasezindaweni ezilayishwe ngomshini (isb., ngesendlalelo soketshezi)59 ngoba ukulayishwa ngomshini kwandisa ingcindezi ephezulu.
Kwenziwe izivivinyo ukuze kuhlolwe imiphumela engaba khona yamasimu ahlukahlukene angokwenyama esakhiweni esincane sezinto eziqinisiwe. Umdwebo osebenzayo wokusetha kokuhlola uboniswe kuMfanekiso 1. Kusetshenziswe i-laser ye-Nd:YAG eqinile esebenza ngemodi yokugijima ngokukhululeka (ubude be-pulse \(\tau _L \sim 150~\upmu \text {s}\ )) . I-laser ngayinye idlula ochungechungeni lwezihlungi ze-neutral density kanye nohlelo lwe-beam splitter plate. Kuye ngokuhlanganiswa kwezihlungi ze-neutral density, amandla e-pulse ku-target ayahlukahluka kusuka ku-\(E_L \sim 20~\text {mJ}\) kuya ku-\(E_L \sim 100~\text {mJ}\) . I-laser beam eboniswa kusuka ku-beam splitter inikezwa i-photodiode ukuze kutholakale idatha ngesikhathi esisodwa, kanye nama-calorimeter amabili (ama-photodiode anesikhathi eside sokuphendula esidlula ku-\(1~\text {ms}\)) asetshenziselwa ukunquma isigameko kuya futhi siboniswe kusuka ku-target, kanye namamitha amabili wamandla (ama-photodiode anempendulo emfushane). izikhathi\(<10~\text {ns}\)) ukunquma isigameko kanye namandla okukhanya abonakalisiwe. Ama-calorimeter namamitha wamandla alinganiswe ukuze anikeze amanani kumayunithi aphelele kusetshenziswa i-thermopile detector Gentec-EO XLP12-3S-H2-D0 kanye nesibuko se-dielectric esifakwe endaweni yesampula. Gxilisa ugongolo phezu komgomo usebenzisa ilensi (i-Antireflection coating ku-\(1.06 \upmu \text {m}\), ubude obuqondile \(160~\text {mm}\)) kanye nomlenze wogongolo endaweni yomgomo 60– \(100~\upmu\text {m}\).
Umdwebo osebenzayo wesimiso sokusetha kokuhlola: 1—i-laser; 2—umqadi we-laser; 3—isihlungi sobuningi obungathathi hlangothi; 4—i-photodiode evumelanisiwe; i-splitter ye-beam engu-5; 6—i-diaphragm; 7—i-calorimeter yomqadi wesigameko; 8 – i-calorimeter yomqadi obonisiwe; 9 – imitha yamandla yomqadi wesigameko; 10 – imitha yamandla yomqadi obonisiwe; 11 – ilensi yokugxila; 12 – isibuko; 13 – isampula; 14 – i-transducer ye-broadband piezoelectric; 15 – i-converter engu-2D; 16 – i-microcontroller yokubeka indawo; 17 – iyunithi yokuvumelanisa; 18 – uhlelo lokuthola idijithali oluneziteshi eziningi olunamazinga ahlukahlukene okusampula; 19 – ikhompyutha yomuntu siqu.
Ukwelashwa nge-Ultrasonic kwenziwa kanje. I-laser isebenza ngemodi yokugijima ngokukhululeka; ngakho-ke ubude be-laser pulse buyi-\(\tau _L \sim 150~\upmu \text {s}\), equkethe ubude obuningi obucishe bube yi-\(1.5~\upmu \text {s} \) ngayinye. Ukuma kwesikhashana kwe-laser pulse kanye ne-spectrum yayo kuqukethe i-envelope ye-frequency ephansi kanye nokuguqulwa kwe-frequency ephezulu, ene-frequency emaphakathi engaba yi-\(0.7~\text {MHz}\), njengoba kuboniswe kuMfanekiso 2.- I-envelope ye-frequency inikeza ukushisa kanye nokuncibilika okulandelayo kanye nokuhwamuka kwezinto, kuyilapho ingxenye ye-frequency ephezulu inikeza ukudlidliza kwe-ultrasonic ngenxa yomphumela we-photoacoustic. I-waveform ye-ultrasonic pulse ekhiqizwa yi-laser inqunywa kakhulu ngesimo sesikhathi sokuqina kwe-laser pulse. Kusuka ku-\(7~\text {kHz}\) kuya ku-\ (2~\text {MHz}\), kanti imvamisa ephakathi ingu-\(~ 0.7~\text {MHz}\). Ama-pulse e-acoustic ngenxa yomphumela we-photoacoustic aqoshwe kusetshenziswa ama-transducer e-broadband piezoelectric enziwe ngamafilimu e-polyvinylidene fluoride. I-waveform eqoshiwe kanye ne-spectrum yayo kuboniswe kuMfanekiso 2. Kufanele kuqashelwe ukuthi ukuma kwama-pulse e-laser kujwayelekile kwe-laser yemodi egijimayo.
Ukusatshalaliswa kwesikhashana kokuqina kwe-laser pulse (a) kanye nesivinini somsindo ebusweni obungemuva besampula (b), ama-spectra e-laser pulse (c) kanye ne-ultrasonic pulse (d) kulinganiselwa kuma-laser pulse angaphezu kwama-300 (ijika elibomvu) kwe-laser pulse eyodwa (ijika eliluhlaza okwesibhakabhaka).
Singahlukanisa ngokucacile izingxenye zemvamisa ephansi kanye nemvamisa ephezulu yokwelashwa kwe-acoustic okuhambisana ne-envelope yemvamisa ephansi ye-laser pulse kanye ne-high-frequency modulation, ngokulandelana. Ama-wavelength amagagasi e-acoustic akhiqizwa yi-laser pulse envelope adlula i-\(40~\text {cm}\); ngakho-ke, umphumela oyinhloko wezingxenye ze-broadband high-frequency zesignali ye-acoustic ku-microstructure kulindeleke.
Izinqubo zomzimba ku-SLM ziyinkimbinkimbi futhi zenzeka ngesikhathi esisodwa ezikalini ezahlukene zendawo nezesikhathi. Ngakho-ke, izindlela eziningi zifaneleka kakhulu ekuhlaziyweni kwethiyori kwe-SLM. Amamodeli ezibalo kufanele aqale abe amaningi ngokomzimba. Imishini kanye ne-thermophysics ye-medium yesigaba esiningi "i-solid-liquid melt" esebenzisana nomoya wegesi ongasebenzi kahle ingachazwa ngempumelelo. Izici zemithwalo yokushisa yezinto ezibonakalayo ku-SLM yilezi ezilandelayo.
Amazinga okushisa nokupholisa afinyelela ku-\(10^6~\text {K}/\text {s}\) /\text{ ngenxa yokukhanya kwe-laser okusendaweni okunamandla afinyelela ku-\(10^{13}~\text {W} cm}^2\).
Umjikelezo wokuncibilika nokuqina uhlala phakathi kuka-1 no-\(10~\text {ms}\), okufaka isandla ekuqineni okusheshayo kwendawo yokuncibilika ngesikhathi sokupholisa.
Ukushisa okusheshayo kobuso besampula kuholela ekwakhekeni kokucindezeleka okuphezulu kwe-thermoelastic kungqimba lobuso. Ingxenye eyanele (kufika ku-20%) yongqimba lwempuphu iyahwamuka kakhulu63, okuholela ekucindezelweni okwengeziwe kobuso ngenxa yokususwa kwe-laser. Ngenxa yalokho, ukucindezeleka okubangelwayo kuphazamisa kakhulu i-geometry yengxenye, ikakhulukazi eduze kwezisekelo kanye nezinto ezincane zesakhiwo. Izinga lokushisa eliphezulu ekufakweni kwe-laser okushukunyiswayo liholela ekwakhiweni kwamagagasi okucindezeleka e-ultrasonic asakazeka kusuka ebusweni aye ku-substrate. Ukuze kutholakale idatha enembile yobuningi ngokucindezeleka kwendawo kanye nokusatshalaliswa kokucindezeleka, kwenziwa ukulingisa kwe-mesoscopic kwenkinga yokuguquguquka kwe-elastic ehlanganiswe nokushisa kanye nokudluliselwa kwesisindo.
Izibalo ezibusayo zemodeli zifaka phakathi (1) izilinganiso zokudlulisa ukushisa ezingazinzile lapho ukuhanjiswa kokushisa kuncike esimweni sesigaba (impuphu, ukuncibilika, i-polycrystalline) kanye nokushisa, (2) ukuguquguquka kokuguquguquka kwe-elastic ngemva kokususwa okuqhubekayo kanye ne-thermoelastic expansion equation. Inkinga yenani lomngcele inqunywa yizimo zokuhlola. I-modulated laser flux ichazwa ebusweni besampula. Ukupholisa kwe-Convective kufaka phakathi ukushintshaniswa kokushisa okuqhubayo kanye ne-evaporative flux. I-mass flux ichazwa ngokusekelwe ekubalweni kwengcindezi yomhwamuko ogcwele wezinto ezihwamukisayo. Ubudlelwano bokucindezeleka kwe-elastoplastic nokucindezeleka kusetshenziswa lapho ukucindezeleka kwe-thermoelastic kuhambisana nomehluko wokushisa. Ngamandla ajwayelekile \(300~\text {W}\), imvamisa \(10^5~\text {Hz}\), i-intermittent coefficient 100 kanye \(200~\upmu \text {m}\ ) yobubanzi be-beam obusebenzayo.
Isithombe 3 sibonisa imiphumela yokulingisa ngezinombolo kwendawo encibilikisiwe kusetshenziswa imodeli yezibalo ye-macroscopic. Ububanzi bendawo yokuhlanganisa buyi-\(200~\upmu \text {m}\) (\(100~\upmu \text {m}\) radius) kanye ne-\(40~\upmu \text {m}\) ukujula. Imiphumela yokulingisa ikhombisa ukuthi izinga lokushisa lobuso liyahlukahluka endaweni ngokuhamba kwesikhathi njenge-\(100~\text {K}\) ngenxa yesici esiphezulu esiqhubekayo sokuguqulwa kwe-pulse. Amazinga okushisa \(V_h\) kanye nokupholisa \(V_c\) alandelana ne-\(10^7\) kanye ne-\(10^6~\text {K}/\text {s}\), ngokulandelana. Lawa manani avumelana kahle nokuhlaziywa kwethu kwangaphambilini64. Umehluko wobukhulu phakathi kwe-\(V_h\) kanye ne-\(V_c\) uphumela ekushiseni okusheshayo kwengqimba yobuso, lapho ukuqhutshwa kokushisa kuya ku-substrate kunganele ukususa ukushisa. Ngakho-ke, ku-\(t=26~\upmu \text {s}\) izinga lokushisa lobuso lifinyelela ku-\(4800~\text {K}\). Ukuhwamuka okukhulu kwezinto kungabangela ukuthi ubuso besampula bucindezelwe kakhulu futhi buqhekeke.
Imiphumela yokulingisa ngezinombolo yendawo yokuncibilika kwe-single laser pulse annealing epuletini lesampula elingu-316L. Isikhathi kusukela ekuqaleni kwe-pulse kuya ekujuleni kwechibi elincibilikisiwe esifinyelela inani eliphakeme kakhulu ngu-\(180~\upmu\text {s}\). I-isotherm\(T = T_L = 1723~\text {K}\) imele umngcele phakathi kwezigaba zoketshezi neziqinile. Ama-isobars (imigqa ephuzi) ahambisana nokucindezeleka kwenzuzo okubalwe njengomsebenzi wokushisa esigabeni esilandelayo. Ngakho-ke, endaweni ephakathi kwama-isoline amabili (ama-isotherms\(T=T_L\) nama-isobars\(\sigma =\sigma _V(T)\)), isigaba esiqinile sibhekene nemithwalo enamandla yemishini, okungaholela ezinguqukweni esakhiweni esincane.
Lo mphumela uchazwe kabanzi kuMfanekiso 4a, lapho izinga lokucindezela endaweni encibilikisiwe lidwetshwa njengomsebenzi wesikhathi nebanga ukusuka ebusweni. Okokuqala, ukuziphatha kokucindezela kuhlobene nokuguqulwa kwamandla okushaya kwe-laser okuchazwe kuMfanekiso 2 ngenhla. Ingcindezi ephezulu \text{s}\) cishe \(10~\text {MPa}\) yabonwa cishe ku-\(t=26~\upmu). Okwesibili, ukushintshashintsha kwengcindezi yendawo endaweni yokulawula kunezici ezifanayo zokunyakaza njengokuphindaphinda kwe-\(500~\text {kHz}\). Lokhu kusho ukuthi amagagasi okucindezela e-ultrasonic akhiqizwa ebusweni bese esakazeka ku-substrate.
Izici ezibalwe zendawo yokuguquguquka eduze kwendawo yokuncibilika ziboniswe ku-Fig. 4b. Ukususwa kwe-laser kanye nokucindezeleka kwe-thermoelastic kukhiqiza amagagasi okuguquguquka okunwebekayo asakazeka ku-substrate. Njengoba kungabonakala esithombeni, kunezigaba ezimbili zokukhiqizwa kokucindezeleka. Ngesikhathi sesigaba sokuqala se-\(t < 40~\upmu \text {s}\), ukucindezeleka kwe-Mises kuphakama kube yi-\(8~\text {MPa}\) ngokuguquguquka okufana nokucindezela kobuso. Lokhu kucindezeleka kwenzeka ngenxa yokususwa kwe-laser, futhi akukho kucindezeleka kwe-thermoelastic okubonwe ezindaweni zokulawula ngoba indawo yokuqala ethintekile ukushisa yayincane kakhulu. Lapho ukushisa kuhlakazeka ku-substrate, indawo yokulawula ikhiqiza ukucindezeleka okuphezulu kwe-thermoelastic ngaphezu kwe-\(40~\text {MPa}\).
Amazinga okucindezeleka aguquliwe atholakele anomthelela omkhulu esibonakalayo se-solid-liquid futhi angaba yindlela yokulawula elawula indlela yokuqina. Ubukhulu bendawo yokuguquguquka bukhulu ngokuphindwe kabili kuya kathathu kunobo bendawo yokuncibilika. Njengoba kuboniswe kuMfanekiso 3, indawo ye-melting isotherm kanye nezinga lokucindezeleka elilingana nokucindezeleka kwesivuno kuyaqhathaniswa. Lokhu kusho ukuthi i-pulsed laser irradiation inikeza imithwalo ephezulu yemishini ezindaweni ezisendaweni enobubanzi obusebenzayo obuphakathi kuka-300 no-(800~\upmu \text {m}\) kuye ngesikhathi esisheshayo.
Ngakho-ke, ukuguqulwa okuyinkimbinkimbi kwe-pulsed laser annealing kuholela emphumeleni we-ultrasonic. Indlela yokukhetha isakhiwo esincane ihlukile uma iqhathaniswa ne-SLM ngaphandle kokulayisha kwe-ultrasonic. Izifunda ezingazinzile eziguquliwe ziholela emijikelezweni yezikhathi ezithile yokucindezela nokwelula esigabeni esiqinile. Ngakho-ke, ukwakheka kwemingcele emisha yokusanhlamvu kanye nemingcele ye-subgrain kuba yinto engenzeka. Ngakho-ke, izakhiwo zesakhiwo esincane zingashintshwa ngamabomu, njengoba kuboniswe ngezansi. Iziphetho ezitholiwe zinikeza ithuba lokuklama i-prototype ye-SLM eqhutshwa yi-ultrasound eqhutshwa yi-pulse modulation. Kulokhu, i-piezoelectric inductor 26 esetshenziswa kwenye indawo ingakhishwa.
(a) Ingcindezi njengomsebenzi wesikhathi, ibalwa emabangeni ahlukene ukusuka ebusweni 0, 20 kanye \(40~\upmu \text {m}\) eceleni kwe-axis yokulinganisa.(b) Ukucindezeleka kwe-Von Mises okuncike esikhathini kubalwa ku-matrix eqinile emabangeni 70, 120 kanye \(170~\upmu \text {m}\) kusuka ebusweni besampula.
Ukuhlolwa kwenziwe kumapuleti ensimbi engagqwali e-AISI 321H anobukhulu \(20\times 20\times 5~\text {mm}\). Ngemva kokushaya kwe-laser ngakunye, ipuleti lihamba \(50~\upmu \text {m}\), kanti okhalweni lwe-laser beam ebusweni obuqondiwe lungaba ngu-\(100~\upmu \text {m}\). Kufika kuma-beam pass amahlanu alandelayo aqhutshwa ngendlela efanayo ukuze kukhuthazwe ukuncibilika kwezinto ezicutshunguliwe ukuze kuhlungwe okusanhlamvu. Kuzo zonke izimo, indawo encibilikisiwe yayibizwa ngokuthi i-sonicated, kuye ngengxenye ye-oscillatory yemisebe ye-laser. Lokhu kuphumela ekunciphiseni okungaphezu kokuphindwe kahlanu endaweni ephakathi kokusanhlamvu. Isithombe 5 sibonisa ukuthi isakhiwo esincane sesifunda esincibilikisiwe nge-laser sishintsha kanjani ngenani lemijikelezo elandelayo yokuncibilikisa (ama-pass).
Ama-subplot (a,d,g,j) kanye no-(b,e,h,k) – isakhiwo esincane sezindawo ezincibilikisiwe nge-laser, ama-subplot (c,f,i,l) – ukusatshalaliswa kwendawo yama-grain anombala. Umthunzi umelela izinhlayiya ezisetshenziselwa ukubala i-histogram. Imibala ihambelana nezindawo zama-grain (bheka ibha yombala phezulu kwe-histogram. Ama-subplot (ac) ahambelana nensimbi engagqwali engalungiswanga, kanti ama-subplot (df), (gi), (jl) ahambelana nama-remelts angu-1, 3 kanye no-5.
Njengoba amandla okushaya kwe-laser engashintshi phakathi kokudlula okulandelayo, ukujula kwendawo encibilikisiwe kuyafana. Ngakho-ke, isiteshi esilandelayo "simboza" ngokuphelele esedlule. Kodwa-ke, i-histogram ikhombisa ukuthi indawo ephakathi nendawo kanye nephakathi nendawo yehla ngenani elikhulayo lokudlula. Lokhu kungabonisa ukuthi i-laser isebenza ku-substrate kunokuba incibilike.
Ukucwengwa kokusanhlamvu kungabangelwa ukupholisa okusheshayo kwechibi elincibilikisiwe65. Kwenziwe olunye uchungechunge lokuhlola lapho ubuso bamapuleti ensimbi engagqwali (321H kanye no-316L) buvezwa khona emisebeni ye-laser yamagagasi aqhubekayo emoyeni (Isithombe 6) kanye ne-vacuum (Isithombe 7). Amandla ajwayelekile e-laser (300 W kanye no-100 W, ngokulandelana) kanye nokujula kwechibi elincibilikisiwe kuseduze nemiphumela yokuhlola ye-laser ye-Nd:YAG kwimodi yokugijima ngokukhululeka. Kodwa-ke, kwabonwa isakhiwo esijwayelekile sekholomu.
Isakhiwo esincane sesifunda esincibilikisiwe nge-laser se-continuous wave laser (amandla angaguquki angu-300 W, isivinini sokuskena esingu-200 mm/s, insimbi engagqwali ye-AISI 321H).
(a) Isakhiwo esincane kanye (b) izithombe ze-electron backscatter diffraction zesifunda esincibilikisiwe nge-laser ku-vacuum nge-laser yamagagasi aqhubekayo (amandla angaguquki angu-100 W, isivinini sokuskena esingu-200 mm/s, insimbi engagqwali ye-AISI 316L)\ (\sim 2~\text {mbar}\).
Ngakho-ke, kuboniswa ngokucacile ukuthi ukuguqulwa okuyinkimbinkimbi kokuqina kwe-laser pulse kunomthelela omkhulu esakhiweni esincane esiphumayo. Sikholelwa ukuthi lo mphumela ungowomshini futhi kwenzeka ngenxa yokukhiqizwa kokudlidliza kwe-ultrasonic okusakazeka kusuka ebusweni obukhanyisiwe bokuncibilika kujule kusampula. Imiphumela efanayo itholakale ku-13, 26, 34, 66, 67 kusetshenziswa ama-transducers e-piezoelectric angaphandle kanye nama-sonotrode ahlinzeka nge-ultrasound enamandla kakhulu ezintweni ezahlukahlukene kufaka phakathi i-Ti-6Al-4V alloy 26 kanye nensimbi engagqwali 34 umphumela. Indlela engenzeka icatshangelwa kanje. I-ultrasound enamandla ingabangela i-acoustic cavitation, njengoba kuboniswe ku-ultrafast in situ synchrotron X-ray imaging. Ukuwa kwama-cavitation bubbles nakho kudala ama-shock wave ezintweni ezincibilikisiwe, okucindezela kwawo kwangaphambili kufinyelela cishe ku-(100~\text {MPa}\)69. Ama-shock wave anjalo angase abe namandla ngokwanele ukukhuthaza ukwakheka kwama-nuclei e-solid-phase aqinile ngobukhulu obukhulu kuketshezi oluningi, okuphazamisa isakhiwo se-columnar grain esijwayelekile se- ukukhiqizwa kwezithasiselo zesendlalelo ngesendlalelo.
Lapha, siphakamisa enye indlela ebangela ukuguqulwa kwesakhiwo nge-sonication enamandla. Ngokushesha ngemva kokuqina, into isezingeni lokushisa eliphezulu eduze nendawo yokuncibilika futhi inokucindezeleka okuphansi kakhulu kwesivuno. Amagagasi amakhulu e-ultrasonic angabangela ukugeleza kwepulasitiki ukushintsha isakhiwo sezinhlamvu sento eshisayo, eqinisiwe nje. Kodwa-ke, idatha yokuhlola ethembekile mayelana nokuxhomekeka kokushisa kokucindezeleka kwesivuno iyatholakala ku-\(T\lesssim 1150~\text {K}\) (bheka Umfanekiso 8). Ngakho-ke, ukuze sihlole lo mbono, senze ukulingisa kwe-molecular dynamics (MD) kokwakheka kwe-Fe-Cr-Ni okufana ne-AISI 316 L steel ukuze sihlole ukuziphatha kokucindezeleka kwesivuno eduze nendawo yokuncibilika. Ukuze sibale ukucindezeleka kwesivuno, sisebenzise indlela yokuphumula kwe-MD shear stress echazwe ku-70, 71, 72, 73. Ekubalweni kokuxhumana kwe-interatomic, sisebenzise i-Embedded Atomic Model (EAM) kusuka ku-74. Ukulingisa kwe-MD kwenziwa kusetshenziswa amakhodi e-LAMMPS 75,76. Imininingwane yokulingisa kwe-MD izoshicilelwa kwenye indawo. Imiphumela yokubala ye-MD yesivuno ukucindezeleka njengomsebenzi wokushisa kuboniswe ku-Fig. 8 kanye nedatha yokuhlola etholakalayo kanye nokunye ukuhlolwa77,78,79,80,81,82.
Ukucindezeleka kwesivuno se-AISI grade 316 insimbi engagqwali ye-austenitic kanye nokwakheka kwemodeli ngokumelene nokushisa kokulingisa kwe-MD. Izilinganiso zokuhlola ezivela ezikhombweni: (a) 77, (b) 78, (c) 79, (d) 80, (e) 81. bheka.(f)82 iyimodeli yokulinganisa yokuxhomekeka kokucindezeleka kwesivuno ekulinganisweni kokucindezeleka okusemgqeni ngesikhathi sokukhiqizwa kwesengezo esisizwa yi-laser. Imiphumela yokulingisa okukhulu kwe-MD kulolu cwaningo ichazwa njenge-\(\vartriangleleft\) yekristalu elilodwa elingenamkhawulo elingenasici kanye ne-\(\vartriangleright\) yama-finite grain kucatshangelwa usayizi we-grain ojwayelekile ngokusebenzisa i-Hall-Petch relation Dimensions\(d = 50~\upmu \text {m}\).
Kungabonakala ukuthi ku-\(T>1500~\text {K}\) ukucindezeleka kwesivuno kwehla ngaphansi kwe-\(40~\text {MPa}\). Ngakolunye uhlangothi, izilinganiso zibikezela ukuthi i-amplitude ye-ultrasonic ekhiqizwa yi-laser idlula i-\(40~\text {MPa}\) (bheka uMfanekiso 4b), okwanele ukuholela ukugeleza kwepulasitiki ezintweni ezishisayo ezisanda kuqina.
Ukwakheka kwesakhiwo esincane sensimbi engagqwali ye-austenitic engu-12Cr18Ni10Ti (AISI 321H) ngesikhathi se-SLM kwahlolwa ngokuhlola kusetshenziswa umthombo we-laser oshukunyiswe ngamandla ayinkimbinkimbi.
Ukwehla kosayizi wezinhlamvu endaweni yokuncibilika kwe-laser kutholakale ngenxa yokuncibilika okuqhubekayo kwe-laser ngemva kokudlula okungu-1, 3 noma 5.
Ukumodela kwe-macroscopic kubonisa ukuthi ubukhulu obulinganisiwe bendawo lapho ukuguqulwa kwe-ultrasonic kungathinta khona ingaphambili lokuqina bufika ku-\(1~\text {mm}\).
Imodeli ye-MD encane kakhulu ikhombisa ukuthi amandla okukhiqiza ensimbi engagqwali ye-AISI 316 austenitic ancishiswe kakhulu abe yi-\(40~\text {MPa}\) eduze nendawo yokuncibilika.
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