1. Introduction to AlNiCo Magnets
AlNiCo (Aluminum-Nickel-Cobalt) magnets are a class of permanent magnet materials known for their excellent temperature stability, high remanence (Br), and low reversible temperature coefficient. They are widely used in high-precision applications such as sensors, motors, aerospace components, and precision instruments. However, due to their brittleness, high hardness, and low toughness, AlNiCo magnets are prone to internal defects during manufacturing, which can significantly affect their magnetic performance and reliability.

1. Introduction to AlNiCo Magnets
AlNiCo (Aluminum-Nickel-Cobalt) magnets are a type of permanent magnet material composed primarily of aluminum (Al), nickel (Ni), and cobalt (Co), with small additions of copper (Cu), titanium (Ti), and other elements to enhance performance. They are known for their high remanence (Br), excellent temperature stability, and low reversible temperature coefficient, making them suitable for high-precision applications such as sensors, motors, and aerospace components.

However, AlNiCo magnets also have inherent drawbacks, including low mechanical strength, high hardness, and brittleness, which significantly impact their machinability. This article explores why AlNiCo magnets require large machining allowances and the dimensional accuracy achievable after machining.

1. Stress-Relief Annealing
Objective:
To eliminate residual stresses generated during manufacturing processes such as casting, forging, machining, or welding, thereby improving dimensional stability and reducing the risk of cracking or deformation.

Alnico magnets, as one of the earliest developed permanent magnetic materials, have unique advantages in high-temperature and high-stability magnetic applications. Grain refinement is an important means to improve the magnetic properties of Alnico magnets. This paper provides an in-depth analysis of the grain refinement processes of cast Alnico magnets, including chemical treatment, mechanical vibration and stirring, and external physical field treatment. It also explores the impact of grain refinement on key magnetic performance indicators such as coercivity, remanence, and maximum magnetic energy product, and looks forward to future research directions in this field.

1. Introduction to Alnico Magnets and Inclusion Challenges
Alnico magnets, composed primarily of aluminum (Al), nickel (Ni), cobalt (Co), and iron (Fe), are renowned for their excellent temperature stability, high remanence, and good corrosion resistance. However, the presence of non-metallic inclusions (NMIs) such as oxides, sulfides, and carbides during melting can significantly degrade their magnetic properties, including coercivity, remanence, and magnetic stability. This article explores the deoxidation and deslagging processes in Alnico melting, focusing on effective inclusion removal techniques and their impact on magnetic performance.

1. Introduction to Sintered Alnico Magnets
Alnico magnets, composed primarily of aluminum (Al), nickel (Ni), cobalt (Co), and iron (Fe), are renowned for their excellent temperature stability, high remanence, and good corrosion resistance. They are widely used in applications such as electric guitars, sensors, meters, and aerospace instruments. Sintered Alnico magnets are manufactured by pressing fine metal powder mixtures into the desired shape and then sintering them at high temperatures to achieve a solid magnet. The pressing process is crucial in determining the final properties of the magnet, with dry pressing and wet pressing being the two primary methods.

1. Introduction to Alnico Magnets
Alnico magnets are a type of permanent magnet composed primarily of aluminum (Al), nickel (Ni), cobalt (Co), and iron (Fe), with small amounts of other elements such as copper (Cu) and titanium (Ti). They are known for their excellent temperature stability, high remanence, and good corrosion resistance, making them suitable for applications in electric guitars, sensors, meters, and aerospace instruments.

The manufacturing process of Alnico magnets typically involves casting or sintering, followed by heat treatment (including annealing and tempering) to optimize their magnetic properties. Among these processes, tempering plays a crucial role in determining the final performance of the magnet.

This paper delves into the core relationship between magnetic field direction and magnet charging direction in the magnetic field orientation process, taking sintered NdFeB and AlNiCo magnets as examples. It analyzes how different orientation processes and charging directions affect the magnetic properties of magnets. Furthermore, it explores the performance loss rate of non-oriented AlNiCo magnets, considering factors such as material composition, production process, and external environmental conditions. The research aims to provide a comprehensive understanding of the magnetic field orientation process and the performance characteristics of AlNiCo magnets, offering valuable references for related fields such as magnet production, motor design, and sensor manufacturing.

Aluminum-nickel-cobalt (AlNiCo) magnets are permanent magnets with excellent magnetic properties, including high Curie temperature, good thermal stability, and high coercivity. They are widely used in sensors, motors, magnetic separators, and precision instruments. However, due to their metallic composition, AlNiCo magnets are susceptible to corrosion, especially in humid or aggressive environments, which can degrade their magnetic performance and mechanical integrity. Surface treatment processes are essential to enhance their corrosion resistance, improve durability, and maintain their magnetic properties. This article discusses three primary surface treatment methods for AlNiCo magnets—passivation, electrophoresis, and electroplating—and compares their corrosion resistance differences.

Aluminum-nickel-cobalt (AlNiCo) alloys are widely used in permanent magnets, sensors, and precision instruments due to their excellent magnetic properties, high Curie temperature, and good thermal stability. However, during the casting process, defects such as shrinkage porosity, shrinkage cavities, and cracks often occur, severely affecting the mechanical properties, magnetic performance, and yield of the rough parts. This article systematically analyzes the root causes of these defects and proposes targeted process improvement measures to provide technical support for high-quality AlNiCo casting production.

1. Introduction
Alnico (Aluminum-Nickel-Cobalt) is a class of permanent magnetic materials known for their high remanence, excellent thermal stability, and strong corrosion resistance. However, its machining presents significant challenges due to its inherent material properties. This article systematically analyzes the core reasons for Alnico's high machining difficulty, explores suitable processing methods, and discusses the risk of demagnetization after machining.

1. Introduction
Alnico (Aluminum-Nickel-Cobalt) magnets are a class of permanent magnetic materials renowned for their exceptional thermal stability, high coercivity, and strong corrosion resistance. Among them, sintered Alnico magnets are widely used in automotive sensors, aerospace, and industrial equipment due to their superior magnetic performance and mechanical properties. The sintering atmosphere is a critical factor influencing the microstructure, density, and magnetic properties of Alnico magnets. This article systematically analyzes the atmosphere requirements for sintering Alnico magnets, explains why vacuum or inert gas environments are essential, and discusses the detrimental effects of oxidation.