A Study on High Strength, High Plasticity, Non-Heat Treated Die-Cast Aluminum Alloy.

Ruizhang Hu,Mingliang Ma,Chun Guo

doi:10.3390/ma15010295

Abstract

The non-heat-treated, die-cast aluminum alloy samples were prepared meticulously via die-casting technology. The crystal structure, microstructure, and phase composition of the samples were comprehensively studied through electron backscatter diffraction (EBSD), metallographic microscopy, spectrometer, and transmission electron microscopy (TEM). The microhardness and tensile properties of the samples were tested. The die-cast samples were found to have desirable properties by studying the structure and performance of the samples. There were no defects, such as pores, cold partitions, or surface cracks, found. The metallographic structure of the samples was mainly α-Al, and various phases were distributed at the grain boundaries. Before heat treating, α-Al grains were mainly equiaxed with a great number of second phase particles at the grain boundaries. After heat treating, the α-Al grains were massive and coarsened, and the second phase grains were refined and uniformly distributed, compared with those before the heat treating. The EBSD results showed that the grain boundary Si particles were solid solution decomposed after heat treatment. The particles became smaller, and their distribution was more uniform. Transmission electron microscopy found that there were nano-scale Al-Mn, Al-Cu, and Cu phases dispersed in the samples. The average microhardness of the samples before heat treating was 114 HV0.1, while, after the heat treating, the microhardness reached 121 HV0.1. The mechanical features of the samples were tremendous, and the obtained die-cast aluminum alloy had non-heat-treatment performance, which was greater than the ordinary die-cast aluminum alloys with a similar composition. The tensile strength of the aluminum alloys reached up to 310 MPa before heat treatment.

Highlights

Aluminum and aluminum-based alloys possess many appropriate properties, including great specific strengths, low densities, good plasticity, excellent mechanical characteristics, low thermal expansion coefficients, good resistance against corrosion in different media, notable electrical/thermal conductivities, easy processing, and recyclability [1,2,3,4]
Once the metals were melted, they were stirred for 10 min, the temperature was raised to 720 ◦C for 30 min, and slag was removed
The sample was well-formed without defects, such as pores, cold barriers, or surface cracks. This indicated that the non-heat-treated, die-cast aluminum alloy designed in this research had a good die-casting performance

Summary

Introduction

Aluminum and aluminum-based alloys possess many appropriate properties, including great specific strengths, low densities, good plasticity, excellent mechanical characteristics, low thermal expansion coefficients, good resistance against corrosion in different media, notable electrical/thermal conductivities, easy processing, and recyclability [1,2,3,4]. Aluminum and its alloys have been looked at for a plethora of applications in the chemicals industry, aerospace infrastructure, aviation, packaging, automobile, shipbuilding, and machinery manufacturing. Very recently, this non-ferrous metal has played a key role in modern industries, such as the automobile industry [5,6]. If a large number of aluminum alloys can be used to replace some steel parts and materials, the weight of the product can be greatly reduced while ensuring its performance, which will greatly reduce energy consumption, save resources, and reduce emissions [11,12,13]. The development of new types of aluminum alloys with high strengths, high plasticity, high toughness, and good processing and manufacturing properties has important research significance

Methods

Results

Conclusion