Study on the fabrication of in-situ TiB2/Al composite by electroslag melting

Jing Xue,Jianbo Ma,Wenyun Wu,Haijun Huang

doi:10.1515/secm-2021-0007

Abstract

Abstract In-situ TiB2 particles can be synthesized via the salts-Al reaction by adding mixed K2TiF6 and KBF4 (Ti/B=1/2) salts into Al melt. In this research, a novel electroslag melting technology was proposed to synthesize TiB2 particles by the salts-Al reaction in order to reduce the reaction time period and purify the melt of composite. The effects of current of electroslag melting on the synthesis of TiB2 particles and mechanical properties of composite were investigated. The results showed that TiB2 particles could be in-situ synthesized by electroslag melting at 600 A for 15min. Compared with 60 min at 850°C of traditional LSM method, the efficiency of preparation was greatly improved. In addition, the dispersion of TiB2 particles in the composite prepared by electroslag melting was improved, meanwhile the non-metallic inclusions in the composite was reduced. The values of YS, UTS and El pct of composite prepared by electroslag melting were higher than that of the composite prepared by traditional LSM method.

Highlights

In-situ TiB2 particles can be synthesized via the salts-Al reaction by adding mixed K2TiF6 and KBF4 (Ti/B=1/2) salts into Al melt
The results showed that TiB2 particles could be in-situ synthesized by electroslag melting at 600 A for 15min
Studies showed that a total synthesis period of in-situ TiB2 particles by the traditional LSM method needed 60 min at 850∘C, and the TiB2 particles existed in the matrix in the form of aggregation

Summary

Raw materials and preparation

The slag agent of electroslag melting used for the preparation of in-situ TiB2/Al composite was a mixture of K2TiF6, KBF4 used to synthesize TiB2 and the basic slag agent used to refine Al melt. The K2TiF6 and KBF4 were mixed with a molar ratio of Ti/B=1/2, and the amount added in slag agent corresponded to form 5wt % TiB2/Al composite. Basic slag agent was common refining agent that contained 47% KCl, 30% NaCl and 23% Na3AlF6 (mass fraction). The consumable electrode was immersed in slag pool, and subjected to electroslag melting to obtain composite ingots with size of Φ70mm×(250~300) mm under a voltage of 15V, a current of 400~700A and a descending speed of 26~126mm/min

Composite preparation

Sample analysis

Effect of melting current on the synthesis of in-situ TiB2 particles

Microstructural features of composites

Findings

Conclusions