In-situ TiC and γ′-Ni3(Al,Ti) triggered microstructural modification and strengthening of Ni matrix composite by reactive hot-press sintering pure Ni and Ti2AlC precursor

JOURNAL OF ALLOYS AND COMPOUNDS

卷:747

Article

Hu, Wenqiang¹  Huang, Zhenying^1,2  Cai, Leping¹  Lei, Cong¹  Zhai, Hongxiang¹  Wo, Shaoshuai¹  Li, Xinkang¹ 

[1] Beijing Jiaotong Univ, Sch Mech & Elect Control Engn, Inst Mat Sci & Engn, Beijing 100044, Peoples R China

[2] Beijing Jiaotong Univ, Minist Educ, Key Lab Vehicle Adv Mfg Measuring & Control Techn, Beijing 100044, Peoples R China

关键词: Ni-based composites;    Ti2AlC;    TiC;    gamma '-Ni-3(Al,Ti);    Microstructure;    Mechanical properties;   

DOI  :  10.1016/j.jallcom.2018.03.069

来源: Elsevier

【 摘 要 】

In the present study, a novel type of Ni-based composites was successfully fabricated from pure Ni and Ti2AlC powder mixtures by hot-press sintering route at 1400 degrees C and 30 MPa. The microstructural analysis indicates that the initial reinforcement Ti2AlC particles transformed into TiC phase, while the additional AleTi atoms decomposed from Ti2AlC diffused into the Ni matrix. The de-intercalated AleTi atoms would subsequently react with Ni to give rise to the formation of gamma'-Ni-3(Al,Ti) precipitates according to element compositions. SEM observations on 30 vol% Ti2AlC/Ni composite after etched showed that L1(2)-centered gamma' phase is ultrafine (about 100 nm) and uniformly distributed in the Ni matrix. The mechanical behavior in relationship with the different fractions of Ti2AlC (10 vol%, 20 vol%, 30 vol% and 40 vol%) were carefully investigated. Yield strength, ultimate compressive strength, flexural strength and Vickers hardness except for fracture strain and toughness increased with the increasing Ti2AlC content; the optimal values for 30Ti(2)AlC/Ni composite were approximately 1056 +/- 29 MPa, 1776 +/- 33MPa, 1284 +/- 59 MPa, and 4.06 +/- 0.07 GPa respectively, with 19.37 +/- 0.75% fracture strain and 26.31 +/- 2 MPa m(1/2) fracture toughness. The enhancement of mechanical properties was attributed to the synergistic effect of fine-grain strengthening, austenitic solid-solution strengthening and dispersion strengthening mechanism. (c) 2018 Elsevier B.V. All rights reserved.

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