We demonstrate giant elastocaloric effect and outstanding refrigeration capacity in a <0 0 1>A textured Ni_(50)Mn_(35)In_(13)Si_(2) alloy with large transformation entropy change △S_(tr) and low-hysteresis △T_...We demonstrate giant elastocaloric effect and outstanding refrigeration capacity in a <0 0 1>A textured Ni_(50)Mn_(35)In_(13)Si_(2) alloy with large transformation entropy change △S_(tr) and low-hysteresis △T_(hys). On unloading from a relatively low compressive stress of 300 MPa, giant adiabatic temperature variation △T_(ad) up to –17.7 K was realized. Moreover, large stress-induced entropy change △S_(σ) of 25.9 J kg^(–1)K^(–1) andgiant refrigeration capacity RC_(σ) of 1330 J kg^(–1) were achieved under the compressive stress of 300 MPa.Simultaneously achieving giant △T_(ad) and outstanding refrigeration capacity indicates that this alloy ispromising to be the candidate material for elastocaloric refrigeration.展开更多
The effects of site occupation on the phase stability,martensitic transformation,and the magnetic and electronic properties of a full series of Ni-Mn-In alloys are theoretically studied by using the ab initio calculat...The effects of site occupation on the phase stability,martensitic transformation,and the magnetic and electronic properties of a full series of Ni-Mn-In alloys are theoretically studied by using the ab initio calculations.Results indicate that the excess atoms of the rich component directly take the sublattices of the deficient components of the Ni2Mn_(1+x)In_(1-x),Ni2-xMn_(1+x)In,and Ni_(2+x)Mn_(1-x)In alloys.Nevertheless,the mixed and indirect site occupations may coexist in the Ni_(2+x)Mn In_(1-x)system.The relevant magnetic configurations of the austenite for the four alloy systems have also been determined.The results show that,except for the austenite in the Ni2-xMn_(1+x)In alloys,which tend to be ferrimagnetic,the other alloys all present ferromagnetic austenite.Thus,the site occupation and associated magnetic states are the crucial influencing factors of the phase stability,martensitic transformation,and the total magnetic moment.The electronic structure of the austenite phase also shows that the covalent bonding plays an important role in the phase stability.The key finding of this work is both Ni2Mn_(1+x)In_(1-x)and Ni_(2+x)Mn In_(1-x)alloys serve as the potential shape memory alloys.展开更多
Composition dependence of martensitic transformations as well as the magnetic properties for the Ni_2 Mn_(1+x)In_(1-x)(0.25≤x≤0.58)alloys were investigated by using the first-principles calculations.Key results demo...Composition dependence of martensitic transformations as well as the magnetic properties for the Ni_2 Mn_(1+x)In_(1-x)(0.25≤x≤0.58)alloys were investigated by using the first-principles calculations.Key results demonstrate that the stability of parent austenite(A)decreases gradually with increasing Mn content whilst it is opposite for the martensitic phase.This causes the total energy difference between the austenite and martensite phases increscent with increasing Mn contents.When x=0.33,the martensite transformation during cooling is PA→FA→NM.When x≥0.42,an intermartensitic transformation occurs from modulated 6 M martensite to non-modulated(NM)martensite with the martensite transformation sequence of PA→FA→6 M→NM.The martensitic transformation from austenite to martensite accompanies the transition from ferromagnetic to ferrimagnetic state.This is a typical magneto-structural coupling transformation.The analysis of the density of states demonstrates that the Ni 3 d state plays an important role in the phase stability.展开更多
Ni-Mn基Heusler合金因其磁–结构相变特性表现出多种功能特性,如磁热效应、磁阻效应与磁场诱导形状记忆效应等,受到广泛关注。本文针对其中的Ni-Mn-In合金展开研究,利用定向凝固技术,制备得到了具有强织构的样品,并利用扫描电子显微镜、...Ni-Mn基Heusler合金因其磁–结构相变特性表现出多种功能特性,如磁热效应、磁阻效应与磁场诱导形状记忆效应等,受到广泛关注。本文针对其中的Ni-Mn-In合金展开研究,利用定向凝固技术,制备得到了具有强织构的样品,并利用扫描电子显微镜、X射线衍射仪、差热扫描量热仪等仪器,对样品的显微结构、相变行为以及性能变化进行了深入研究。研究表明,在室温下样品为L21立方奥氏体,且定向凝固后得到了织构。通过对喷铸与定向凝固样品的相变行为进行分析,发现定向凝固后相变温度显著上升(从约170 K升高至约200 K),居里温度则基本保持不变。同时,定向凝固样品的相变宽度更窄,即相变更剧烈,相变的热滞后行为也得到显著改善(从19.8 K降低至12.5 K)。此外,对定向凝固样品的热膨胀性能进行了测试:在升温奥氏体相变过程(215~230 K)中,沿生长方向(LD)发现了显著的负热膨胀现象,热膨胀系数αL = −259.6 ppm/K,而垂直于生长方向(ND)则呈现正热膨胀行为,热膨胀系数高达452.7 ppm/K,远高于喷铸样品的173.9 ppm/K。综上所述,定向凝固方法对Ni-Mn-In合金的相变行为起到显著调控作用,并成功在该体系合金中获得了负热膨胀性能。Ni-Mn-based Heusler alloys have attracted widespread attention due to their magnetic-structural phase transition characteristics, which exhibit various functional properties such as the magnetocaloric effect, magnetoresistance, and magnetic-field-induced shape memory effect. This paper focuses on the Ni-Mn-In alloy, where directional solidification technology was used to prepare samples with strong texture. The microstructure, phase transition behavior, and performance changes of the samples were thoroughly studied using instruments such as scanning electron microscopy, X-ray diffraction, and differential scanning calorimetry. The research shows that at room temperature, the sample is in the L21 cubic austenite phase, and after directional solidification, a texture is obtained. By analyzing the phase transition behavior of both spray-cast and directionally solidified samples, it was found that the phase transition temperature significantly increases after directional solidification (rising from approximately 170 K to around 200 K), while the Curie temperature remains nearly unchanged. Meanwhile, the phase transition width of the directionally solidified sample is narrower, indicating a more abrupt transition, and the thermal hysteresis behavior of the phase transition is also significantly improved (reduced from 19.8 K to 12.5 K). Additionally, the thermal expansion properties of the directionally solidified samples were tested: during the austenitic phase transition process (215~230 K) upon heating, a significant negative thermal expansion phenomenon was observed along the growth direction (LD), with a thermal expansion coefficient of αL = −259.6 ppm/K, whereas perpendicular to the growth direction (ND), positive thermal expansion behavior was exhibited, with a thermal expansion coefficient as high as 452.7 ppm/K, which is much higher than the 173.9 ppm/K of the spray-cast sample. In conclusion, the directional solidification method plays a significant role in modulating the phase transition behavior of Ni-Mn-In alloys and, for the first time, negative thermal expansion properties were obtained in this alloy system.展开更多
基金This work was financially supported by the National Natural Science Foundation of China(Nos.51771048,52171005)the Liaoning Revitalization Talents Program(Nos.XLYC1907082,XLYC1907046,XLYC1802023).
文摘We demonstrate giant elastocaloric effect and outstanding refrigeration capacity in a <0 0 1>A textured Ni_(50)Mn_(35)In_(13)Si_(2) alloy with large transformation entropy change △S_(tr) and low-hysteresis △T_(hys). On unloading from a relatively low compressive stress of 300 MPa, giant adiabatic temperature variation △T_(ad) up to –17.7 K was realized. Moreover, large stress-induced entropy change △S_(σ) of 25.9 J kg^(–1)K^(–1) andgiant refrigeration capacity RC_(σ) of 1330 J kg^(–1) were achieved under the compressive stress of 300 MPa.Simultaneously achieving giant △T_(ad) and outstanding refrigeration capacity indicates that this alloy ispromising to be the candidate material for elastocaloric refrigeration.
基金financially supported by the National Natural Science Foundation of China(No.51771044)the Natural Science Foundation of Hebei Province(No.E2019501061)+2 种基金the Fundamental Research Funds for the Central Universities(No.N2023027)the Programme of Introducing Talents of Discipline Innovation to Universities 2.0(the 111 Project of China 2.0,No.BP0719037)the Liao Ning Revitalization Talents Program(No.XLYC1802023)。
文摘The effects of site occupation on the phase stability,martensitic transformation,and the magnetic and electronic properties of a full series of Ni-Mn-In alloys are theoretically studied by using the ab initio calculations.Results indicate that the excess atoms of the rich component directly take the sublattices of the deficient components of the Ni2Mn_(1+x)In_(1-x),Ni2-xMn_(1+x)In,and Ni_(2+x)Mn_(1-x)In alloys.Nevertheless,the mixed and indirect site occupations may coexist in the Ni_(2+x)Mn In_(1-x)system.The relevant magnetic configurations of the austenite for the four alloy systems have also been determined.The results show that,except for the austenite in the Ni2-xMn_(1+x)In alloys,which tend to be ferrimagnetic,the other alloys all present ferromagnetic austenite.Thus,the site occupation and associated magnetic states are the crucial influencing factors of the phase stability,martensitic transformation,and the total magnetic moment.The electronic structure of the austenite phase also shows that the covalent bonding plays an important role in the phase stability.The key finding of this work is both Ni2Mn_(1+x)In_(1-x)and Ni_(2+x)Mn In_(1-x)alloys serve as the potential shape memory alloys.
基金supported by the National Natural Science Foundation of China(Grant No.51771044)Natural Science Foundation of Hebei Province(No.E2019501061)+2 种基金Fundamental Research Funds for the Central Universities(No.N2023027)Programme of Introducing Talents of Discipline Innovation to Universities 2.0(the 111Project of China 2.0,No.BP0719037)the Liao Ning Revitalization Talents Program(Grant No.XLYC1802023)。
文摘Composition dependence of martensitic transformations as well as the magnetic properties for the Ni_2 Mn_(1+x)In_(1-x)(0.25≤x≤0.58)alloys were investigated by using the first-principles calculations.Key results demonstrate that the stability of parent austenite(A)decreases gradually with increasing Mn content whilst it is opposite for the martensitic phase.This causes the total energy difference between the austenite and martensite phases increscent with increasing Mn contents.When x=0.33,the martensite transformation during cooling is PA→FA→NM.When x≥0.42,an intermartensitic transformation occurs from modulated 6 M martensite to non-modulated(NM)martensite with the martensite transformation sequence of PA→FA→6 M→NM.The martensitic transformation from austenite to martensite accompanies the transition from ferromagnetic to ferrimagnetic state.This is a typical magneto-structural coupling transformation.The analysis of the density of states demonstrates that the Ni 3 d state plays an important role in the phase stability.
文摘Ni-Mn基Heusler合金因其磁–结构相变特性表现出多种功能特性,如磁热效应、磁阻效应与磁场诱导形状记忆效应等,受到广泛关注。本文针对其中的Ni-Mn-In合金展开研究,利用定向凝固技术,制备得到了具有强织构的样品,并利用扫描电子显微镜、X射线衍射仪、差热扫描量热仪等仪器,对样品的显微结构、相变行为以及性能变化进行了深入研究。研究表明,在室温下样品为L21立方奥氏体,且定向凝固后得到了织构。通过对喷铸与定向凝固样品的相变行为进行分析,发现定向凝固后相变温度显著上升(从约170 K升高至约200 K),居里温度则基本保持不变。同时,定向凝固样品的相变宽度更窄,即相变更剧烈,相变的热滞后行为也得到显著改善(从19.8 K降低至12.5 K)。此外,对定向凝固样品的热膨胀性能进行了测试:在升温奥氏体相变过程(215~230 K)中,沿生长方向(LD)发现了显著的负热膨胀现象,热膨胀系数αL = −259.6 ppm/K,而垂直于生长方向(ND)则呈现正热膨胀行为,热膨胀系数高达452.7 ppm/K,远高于喷铸样品的173.9 ppm/K。综上所述,定向凝固方法对Ni-Mn-In合金的相变行为起到显著调控作用,并成功在该体系合金中获得了负热膨胀性能。Ni-Mn-based Heusler alloys have attracted widespread attention due to their magnetic-structural phase transition characteristics, which exhibit various functional properties such as the magnetocaloric effect, magnetoresistance, and magnetic-field-induced shape memory effect. This paper focuses on the Ni-Mn-In alloy, where directional solidification technology was used to prepare samples with strong texture. The microstructure, phase transition behavior, and performance changes of the samples were thoroughly studied using instruments such as scanning electron microscopy, X-ray diffraction, and differential scanning calorimetry. The research shows that at room temperature, the sample is in the L21 cubic austenite phase, and after directional solidification, a texture is obtained. By analyzing the phase transition behavior of both spray-cast and directionally solidified samples, it was found that the phase transition temperature significantly increases after directional solidification (rising from approximately 170 K to around 200 K), while the Curie temperature remains nearly unchanged. Meanwhile, the phase transition width of the directionally solidified sample is narrower, indicating a more abrupt transition, and the thermal hysteresis behavior of the phase transition is also significantly improved (reduced from 19.8 K to 12.5 K). Additionally, the thermal expansion properties of the directionally solidified samples were tested: during the austenitic phase transition process (215~230 K) upon heating, a significant negative thermal expansion phenomenon was observed along the growth direction (LD), with a thermal expansion coefficient of αL = −259.6 ppm/K, whereas perpendicular to the growth direction (ND), positive thermal expansion behavior was exhibited, with a thermal expansion coefficient as high as 452.7 ppm/K, which is much higher than the 173.9 ppm/K of the spray-cast sample. In conclusion, the directional solidification method plays a significant role in modulating the phase transition behavior of Ni-Mn-In alloys and, for the first time, negative thermal expansion properties were obtained in this alloy system.
