Bhaskar Majumdar博士

教授

材料与冶金工程

majumdar@zqosn.net
575 - 835 - 5152
琼斯104年

视频:10分钟研究报告

研究领域

Primary research interests are in structure-property relations of materials, and microstructure optimization through thermo-mechanical processing.

母亲ials that have been investigated include Ni-base superalloys, metallic composites, high strength nano-structured Al-alloys, fiber and CNT based polymeric composites, Ti-alloys, contact and adhesion at rough surfaces, and most recently shape memory 合金和磁热金属间合金.

In recent years, the research has focused more heavily on XRD and neutron diffraction characterization methods for quantitative phase analysis, and also to understand internal stress and texture evolution in multiphase materials following thermomechanical processing. 的 research is complemented with analytical/FEM analysis to predict deformation response 同时优化加工参数.

教育

Ph.D. 材料科学， 罗切斯特大学， 罗切斯特，纽约州14627,1980

M.S. 机械工程 印度科学研究所， 班加罗尔，印度，1975年

B.科技. 机械工程 印度理工学院， 1972年，印度坎普尔

最近研究的简明语言摘要

无铅锡电镀中晶须的抑制

的 growth of tin whiskers on a wide range of Sn-coated electronic components pose catastrophic short-circuit problems in many long term applications, e.g.，在航空航天领域; 国防、核能和交通. In the past, this was largely mitigated by adding a few percent Pb to Sn, but that is no longer possible due to the worldwide ban on Pb. Through our work on NSF award CMMI-1335199, we have demonstrated Indium as an alloying element not only mitigates, but actually 消除了 Sn-whisker增长. This has been a major breakthrough following 50 years of research aimed at eliminating Sn whiskers in solder applications. 此外，我们已经确定 a key mechanism responsible for whisker mitigation - that Indium leads to alteration of the structure and chemistry of the 3-4 nm surface oxide on Sn, along with enriched In in the near surface (20-70nm depth) and grain boundary regions. 从本质上讲,我们 show that Indium compromises the tenacity of the oxide coating. 我们观察到相似 segregation in Pb doped Sn, and it constitutes a major departure from conventional understanding of the role of Pb in Sn whisker mitigation.

Additional fundamental studies of mechanisms such as texture changes are in progress, and a goal is to obtain a general understanding of whisker mitigation not only in Sn films on Cu, but also in Al films on Si, Cd films on alloy steels, etc. 美国临时政府 patent application has been filed for Sn-In films.

发明

B.S. Majumdar, S. Bhassyvasantha和L. 苏尔. Tin-Indium alloy electroplating solution, US Provisional 专利申请号62/589,151,2017年提交.

出版物

S. Bhassyvasantha N. Fredj,年代.D. 达斯·马哈帕特拉，W. 詹宁斯,我. 杜塔, B.S. Majumdar. Whisker mitigation mechanisms in indium doped tin thin films: Role of the surface, Journal of 电子ic 母亲ials (2017), under review.

S. Das塔, B.S. Majumdar, I. 杜塔年代. Bhassyvasantha. Eliminating Whisker Growth by Indium Addition in Electroplated Sn on Copper Substrate, J. 电子. 母亲. 46 (2017) 4062-4075.

S. 巴纳吉,我. 杜塔, B.S. Majumdar. A molecular dynamics evaluation of the effect of dopant addition on grain boundary 锡中的扩散:对晶须生长的影响,母亲. Sci. 英格. struct. 母亲. 道具. Microstruct. 过程. 666 (2016) 191-198.

L. Meinshausen,年代. Bhassyvasantha, B.S. Majumdar, I. 杜塔. Influence of Indium Addition on Whisker Mitigation in Electroplated Tin Coatings on 铜基板, J. 电子. 母亲. 45 (2016) 791-801.

Magnetocaloric alloys based on non-stoichiometric Ni2MnGa alloys – MCE enhancements through thermomechanical texturing and elemental doping

Magnetocaloric materials have gained significant interest as an environment friendly and efficient solid state refrigeration technology. 我们一直在研究赫斯勒合金，主要是非化学计量的Ni₂MnGa system that rely on magnetic field induced first order structural transformation (‘magnetostructural transformation’) for improved magnetocaloric effect (MCE). 的 work was originally funded by the Army 研究 Laboratories. 的magnetostructural transformation temperature is sensitively dependent on composition, so that alloying chemistry have to be optimized for martensitic transformation close to RT. 此外, we have observed significant MCE increase (up to 80%) following stress assisted thermally cycling of samples, and have demonstrated that one primary mechanism responsible for the increased MCE is the development of preferred crystallographic orientation in 马氏体相. 的 rationale for this approach derived from our previous work 对形状记忆NiTi样品，其中原位 neutron diffraction work LANL showed favorable texture when a sample was cooled from the austenite to the martensite under low applied stress – an effect due to very low 相变温度下的剪切模量. 这项工作最初是通过 ARO和后来的NSF.

In more recent work we have been studying the influence of elemental doping, in order to bring the magnetostructural transformation from about 60 C to RT while 同时增强MCE.

出版物

M.V. 麦克劳德, B.S. Majumdar, Z. 奥. Magnetocaloric Improvements in Doped Heusler Alloys， MRS进展2 (2017)3453-3458 (2017).

M.V. 麦克劳德,.K. Giri B.A. 帕特森,C.L. 丹尼斯,我. 周,S-C. 沃格尔, B.S. Majumdar等。. Magnetocaloric response of non-stoichiometric Ni2MnGa alloys and the influence of 晶体结构，物质学报; 97:245-56 (2015).

L. 周,. Giri K. 曹,H. 海因里希, B. Majumdar, Y. 孙. Microstructural and Crystallographic Characterization of Ni2+x Mn1-x Ga Alloys (x =0.14, 0.16, 0.19, 0.22和0.24)透射电镜, Metallurgical and 母亲ials Transactions E 1, 239-246 (2014).

A.K. Giri B.A. 帕特森,M.V. 麦克劳德,C.L. 丹尼斯, B.S. Majumdar, K.C. 曹,R.D. Shull. Effect of crystallographic alignment on the magnetocaloric effect in alloys near the Ni2MnGa stoichiometr[j]，应用物理学报17 (7)(2013).

B. Ye, B.S. Majumdar, I. 杜塔. Texture development and strain hysteresis in a NiTi shape-memory alloy during thermal 负载下循环，物质学报. 57 (2009) 2403-2417.

B. Ye*, B.S. Majumdar, I. 杜塔. Texture memory and strain-texture mapping in a NiTi shape memory alloy,:. 理论物理. 列托语. 91 (2007) 061918.

论文

Structural and Magnetic 道具erties of Magnetocaloric Ni-Mn-Ga Heusler Alloys as Influenced 元素掺杂和处理 - M.V. 麦克劳德(2017).