Co and Ti effect on hot workability of phosphor bronze

• Published in: Journal of alloys and compounds 2022-05, Vol.903, p.163778, Article 163778
• Main Authors: Shin, Hyeon Seok, Han, Seung Zeon, Choi, Eun-Ae, Ahn, Jee Hyuk, Kim, Sangshik, Lee, Jehyun
• Format: Article
• Language: English
• Subjects: Alloys; Bronze; Co-Ti intermetallic compound; Copper; Copper base alloys; Crack initiation; Cu-Sn alloy; Deformation; Density functional theory; Grain boundaries; High temperature; Hot pressing; Hot rolling; Hot workability; Hot working; Intermetallic compounds; Phosphor bronzes; Sn segregation; Solidification; Tin; Titanium base alloys
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2022.163778

•Phosphor bronze with Co and Ti has remarkable hot workability.•Dissolved Co hinders the diffusion and segregation of Sn in the matrix.•Co-Ti intermetallic stabilized grain boundaries where Sn segregation occurs. It is known that Cu-Sn alloy is difficult to hot working due to Sn segregation which occurs during solidification. Sn segregation is formed at grain boundary and it acts as crack initiation site during hot working. To suppress Sn segregation at grain boundary, density functional theory calculations were performed to search the proper elements that can stabilize Sn in Cu matrix. Based on the simulations, Co-Sn pairs are the most stable in Cu matrix, meaning that Co atoms can effectively stabilize Sn atoms in Cu matrix. To enhance the Co effect, we search the additional element to stabilize Co atom in Cu. As a result, Co atoms can stabilize more in form of Co-Ti pair in Cu. Three alloys, Cu-8Sn-0.1 P alloy (wt%), this alloy with 0.23 Co and 0.18 Ti, and alloy with 0.45 Co and 0.36 Ti were prepared. Co and Ti addition in Cu-Sn-P alloy formed the Co-Ti intermetallic compound and improved the uniformity of Sn concentration in matrix and lead reducing the Sn segregation at grain boundary. The reduction of Sn concentration difference in matrix resulted in uniform deformation and prevented crack initiation during high temperature deformation. As a result, Cu-Sn-P alloy with Co and Ti alloy prevented cracking after a hot compression test or hot rolling at 850 °C.