Heat Treatment of NiTi Alloys Fabricated Using Laser Powder Bed Fusion (LPBF) from Elementally Blended Powders

被引：23

作者：

Chmielewska, Agnieszka ^{[1
]}

Wysocki, Bartlomiej ^{[2
]}

Kwasniak, Piotr ^{[2
]}

Kruszewski, Miroslaw Jakub ^{[1
]}

Michalski, Bartosz ^{[1
]}

Zielinska, Aleksandra ^{[1
]}

Adamczyk-Cieslak, Boguslawa ^{[1
]}

Krawczynska, Agnieszka ^{[1
]}

Buhagiar, Joseph ^{[3
]}

Swieszkowski, Wojciech ^{[1
]}

机构：

[1] Warsaw Univ Technol, Fac Mat Sci & Engn, Woloska 141 Str, PL-02507 Warsaw, Poland

[2] Cardinal Stefan Wyszynski Univ Warsaw, Ctr Digital Sci & Technol, Woycickiego 1-3, PL-01938 Warsaw, Poland

[3] Univ Malta, Dept Met & Mat Engn, MSD 2080, Msida, Malta

来源：

MATERIALS | 2022年 / 15卷 / 09期

关键词：

elemental powders; heat treatment; in situ alloying; laser powder bed fusion; nickel-titanium; pre-mixed powders; SHAPE-MEMORY ALLOYS; TRANSFORMATION BEHAVIOR; MECHANICAL-PROPERTIES; CRYSTAL-STRUCTURE; MICROSTRUCTURE; REFINEMENT; TITANIUM; NICKEL;

D O I：

10.3390/ma15093304

中图分类号：

O64 [物理化学（理论化学）、化学物理学];

学科分类号：

070304 ; 081704 ;

摘要：

The use of elemental metallic powders and in situ alloying in additive manufacturing (AM) is of industrial relevance as it offers the required flexibility to tailor the batch powder composition. This solution has been applied to the AM manufacturing of nickel-titanium (NiTi) shape memory alloy components. In this work, we show that laser powder bed fusion (LPBF) can be used to create a Ni55.7Ti44.3 alloyed component, but that the chemical composition of the build has a large heterogeneity. To solve this problem three different annealing heat treatments were designed, and the resulting porosity, microstructural homogeneity, and phase formation was investigated. The heat treatments were found to improve the alloy's chemical and phase homogeneity, but the brittle NiTi2 phase was found to be stabilized by the 0.54 wt.% of oxygen present in all fabricated samples. As a consequence, a Ni2Ti4O phase was formed and was confirmed by transmission electron microscopy (TEM) observation. This study showed that pore formation in in situ alloyed NiTi can be controlled via heat treatment. Moreover, we have shown that the two-step heat treatment is a promising method to homogenise the chemical and phase composition of in situ alloyed NiTi powder fabricated by LPBF.

引用

页数：15

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