Rapid solidification of shape memory alloy Cu-11.85Al-3.2Ni-3Mn by spray forming

• Grant number: 12/22839-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: January 01, 2013
• End date: December 31, 2016
• Field of knowledge: Engineering - Materials and Metallurgical Engineering - Physical Metallurgy
• Principal Investigator: Claudio Shyinti Kiminami
• Grantee: Fernando Henrique Paes de Almeida
• Host Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil

Abstract

The alloys with shape memory effect are able to recover its original shape after being deformed plastically. The technological applications of these alloys cover several areas such as medical, security, and robotics. The most commonly used alloys are based on composite Ni-Ti. However, these alloys are very reactive with oxygen and also exhibit a large hysteresis and thermal stress. Moreover, the Cu based alloys have advantages over Ni-Ti alloys, both by the reduced cost of the alloy elements, such as by lower hysteresis and thermal stress, and low reactivity with oxygen. The main difficulty in producing such alloys is the requirement of high cooling rates to avoid the beta phase formation, which decomposes phases alpha and gamma2 at 565°C, deteriorating the properties of the material. This transformation can be avoided during rapid solidification allowing the beta phase undergoes martensitic transformation only at temperatures above room temperature. Moreover, the conformation spray is a rapid solidification process in which a stream of molten metal is atomized by injecting an inert gas at high speed, generating drops of various sizes, which are rapidly driven toward a metallic or ceramic substrate by collecting them in solid, liquid, or partially solid, generating a coherent deposit almost entirely dense. During the process, rates on the order of 1000-100000 K/s can be achieved. Thus, this design proposes to use the spray forming process in processing the copper base alloy Cu-3.2Ni-11.85Al-3Mn targeting the shape memory effect. (AU)