Valery Levitas, Schafer Professor and faculty member of aerospace engineering and of mechanical engineering, aerospace engineering PhD student Hao Chen, and Assistant Professor Liming Xiong published their work in Physical Review Letters, a highly ranked physics journal.
In the paper, the researchers predicted and studied a new type of first-order phase transformations. Levitas, Xiong, and Chen found that if they apply special different stresses along different directions during transformation, the phase transition will occur homogeneously.
The energy barrier between phases that exists during normal phase transformation, disappears during the new homogenous transition. This means that that the entire volume of the material can be homogeneously compressed/decompressed between two phases and there is no need for nucleation and growth.
“There are large stresses at interfaces that can damage material as phase grows during traditional transformations. When you do direct-reverse phase transformation many times, there can be material damage and energy dissipation and then it will stop working,” Levitas said.
The three researchers found that by applying special stresses from different sides, the transformation can occur without the drawbacks of traditional phase transformation. “There are no nuclei, there are no interfaces, there is no damage, and there is no energy dissipation,” Levitas said.
With no damage or energy dissipation, the material can serve much longer and without requiring the need for extra energy. This may revolutionize numerous practical applications, such as for actuation and biomedical applications utilizing shape memory alloys and energy transformation with caloric materials.
The theoretical work is the first of it’s kind and paves the way for new fundamental and applied directions in phase transformations.
Valery Levitas, Profesa wa Schaefer na mwanachama wa kitivo cha uhandisi wa anga na uhandisi wa mashine, mwanafunzi wa PhD wa uhandisi wa anga na anga Hao Chen, na Profesa Msaidizi Liming Xiong walichapisha kazi yao katika Fasihi ya Kurudia Barua, jarida la fizikia lenye nafasi ya juu. Katika karatasi hiyo, watafiti walitabiri na kuchunguza aina mpya ya mabadiliko ya awamu ya utaratibu wa kwanza. Levitas, Xiong, na Chen waligundua kwamba ikiwa watatumia mkazo maalum tofauti katika mwelekeo tofauti wakati wa mabadiliko, mabadiliko ya awamu yatatokea kwa usawa. kizuizi nishati kati ya awamu ambayo ipo wakati wa awamu ya kawaida mabadiliko, kutoweka wakati wa mpito mpya homogeneous. Hii ina maana kwamba kiasi nzima ya nyenzo inaweza homogeneously compressed au decompressed kati ya awamu mbili na hakuna haja ya nucleation na ukuaji. <unk>Kuna mikazo mikubwa katika interfaces ambayo inaweza kuharibu nyenzo kama awamu inakua wakati wa mabadiliko ya jadi. Wakati unafanya moja kwa moja-reverse awamu ya mabadiliko mara nyingi, kunaweza kuwa na uharibifu wa vifaa na dissipation nishati na kisha itasimama kufanya kazi, "Levitas alisema. Watafiti hao watatu waligundua kwamba kwa kutumia mkazo maalum kutoka pande tofauti, mabadiliko yanaweza kutokea bila kasoro za mabadiliko ya awamu ya jadi. "Hakuna nyuklia, hakuna interfaces, hakuna uharibifu, na hakuna dissipation nishati", alisema Levitas. Bila uharibifu au uharibifu wa nishati, nyenzo inaweza kutumika kwa muda mrefu zaidi na bila kuhitaji nishati ya ziada. Hii inaweza kuleta mapinduzi katika matumizi mengi ya vitendo, kama vile kwa ajili ya uendeshaji na matumizi ya biomedical kutumia alloys kumbukumbu umbo na mabadiliko ya nishati na vifaa caloric. Kazi ya nadharia ni ya kwanza ya aina yake na inafungua njia kwa ajili ya mwelekeo mpya ya msingi na kutumika katika mabadiliko ya awamu.